Bible not reliable

You say you believe in Moses and Jesus, so why don't you follow the Bible?

Muslims believe all the prophets spoke the truth, including Abraham, Moses, Jesus, and so many others. We see them similarly as we see Muhammad, may the peace and blessings of Allah be upon all those who Allah selected as examples for us. There are at least 25 mentioned in al-Quran and based on sayings, there have been thousands spread throughout the millennia. When it comes to the Bible, we don't denigrate it, or shouldn't, but this question's premise is true: we don't seek guidance in it despite it's association with prophets we believe in and despite that Allah states in al-Quran that it is Allah who sent the Torah and the Gospel. So, it's a good question because based on all that it seems Muslims would read the Bible regularly. There is a simple short answer, which I'll start with, but then I'll go inside the Bible by looking at a few versus from an Islamic perspective.

The short but blunt answer & when Muslims do read it

A companion of the Prophet, peace on him, was reading from the Torah. The Prophet told him that if Moses were on the earth at that time, he would judge by his sunnah (Muhammad's example of applying al-Qur'an). That's no slight to Moses, who is also one of the five mostly greatly tested Messengers. But this is now and that was then. The beliefs the prophets came with are all the same, but the manner of application varies by Allah's wisdom and based on the people and events of a given time. To put it very simply, the Bible is out of date. Certainly someone will say the same about al-Qur'an, but that's another discussion. As for this one, it raises the question why would a Muslim read the Bible? Putting historical relevance and reverence aside, what is the need for it in a Muslim's religious life? In al-Qur'an, Allah does refer to the Torah of Moses and the Injeel of Jesus, but by way of directing Jews and Christians to accept the latest revelation. A Muslim may wonder, if the Bible were sufficient at this time, why would have Allah revealed al-Qur'an? We're happy with what we've got, perhaps like Christians are happy with their Bible.

But there's a difference, I would argue. Besides al-Qur'an, which is the Speech of Allah, Islam is also defined via ahadith, which comprise a detailed record of how a prophet lived and taught, as well as the lives and stories of their followers and their kids and kids' kids, providing a community perspective in the revelation, as well. Without that, we don't regard al-Qur'an as the complete message. Similarly, the Bible, without a sure and complete record of how it was implemented, can't be interpreted according to God's intent. So, it would look incomplete to a Muslim even at that time. In the chapter called The Table Spread, Allah says, "Today I have completed your religion for you, and I have perfected My favor on you, and I am satisfied with Islam as a religion for you." The situation doesn't leave Muslims shopping for more core material.

However, Muslims are not totally ignorant of the Bible, and some do or at least have read some or all of it. There may be some Muslims (and "Nation of Islam") who read or upload the Bible as guidance, but that's not the norm. There are a few who learn some of the verses which appear to them to support Islam versus Christianity, and they'll use those to challenge Christians; I'm not confident there's much value in that, but I don't know. Sometimes I feel like Muslims mention those verses to try to impress other Muslims, which would be very silly. I will discuss some of those versus below, but I don't claim them as proof of anything because one person of one religion pressing someone of anther religion about their book can turn into a dog chasing it's tail. Allah says, "Laa ikraha fiddeen." It's that no one can meaningfully compel another person to believe a given way. Moreover, the scholars of Islam have advised against this, especially among the majority of Muslims who are unqualified to discuss, let alone debate, Bible versus. Rather, we share the information and people draw their own conclusions.

As for me, personally, I have several English versions of the Bible in my house for reference, plus one translated in Arabic. I can't read that one much at all apart from Allaah, the Arabic word for God (and sister to Elohim and Alaaha from Hebrew and Aramaic). So, again, it's not that we don't believe all the revelations are from the same God. They are.

A look inside the Bible

When it comes to the Bible, itself, there are factors that affect the level of accuracy and creditably with which these messages have reached us. The general principle, thus, is not to say it's wrong and not to say it's right, but to just leave it alone as a mixture where the reliable parts aren't always distinguishable from the unreliable parts.

Originally, yes, the Torah and the Injeel (Gospel) were parts of an intact message to specific people, the Jews of Moses and those of Jesus, respectively. We also believe Allah revealed scrolls to Abraham and the Saboor (Psalms) to David. Since that time and before the revelation of al-Qur'an, there was a progressive adulteration in the interpretation of God's revelations. The era of Roman Emperor Constantine was especially harmful to Jesus's legacy on earth, whereas it seems likely it was Jews, themselves who tampered with the scripture.

The modern New Testament (NT) versions are composite translations from over 3200 Greek manuscripts/fragments, 8000 in Latin, and about 1000 in various other languages. Those copies differ in various ways, so translators made choices in favor of certain ones over others. As to the accuracy level of the copies themselves, since they are not the originals (lost), that's an unknown. On top of that, there is only one verse in the entire NT available in the language Jesus spoke (Aramaic). This is not the picture of reliability already. Moreover, the books themselves do not appear to agree in their messages. Compare, for instance, James, with the ideology Paul, a former persecutor who says he met Jesus in a vision. The division between the thinking of Paul and Barnabas is also well documented. What's not documented well are the histories or even identities of many of the other writers, including even Matthew, Mark, Luke, and John. The canonization process, as well, took place long after the ascension of Jesus, and could be criticized from multiple standpoints. As for the trinity doctrine, specifically, The New Catholic Encyclopedia states, "It was the product of 3 centuries of doctrinal development." At a point as a non-Muslim I doubted the message of Jesus accurately wound it's way through that maze. Now, as a Muslim, I know it did not. Allah says, "And [beware the Day] when Allah will say, 'O Jesus, Son of Mary, did you say to the people, 'Take me and my mother [note Catholic veneration, etc.] as deities besides Allah ?'' He will say, 'Exalted are You! It was not for me to say that to which I have no right. If I had said it, You would have known it. You know what is within myself, and I do not know what is within Yourself. Indeed, it is You who is Knower of the unseen'" [al-Qur'an 5:116]. Furthermore, there are several ayaat and ahadith which make it clear al-Qur'an and as-Sunnah are sufficient guidance without resorting to other religious books to define Islam, though apparent wisdom may be taken from any number of places as we go through life.

As for the Old Testament, I find great relief in knowing the major sins of prophets are lies, such as what is attributed to David, Solomon, and Lot, peace be upon all of them. I'll let Christians, themselves, interpret Jeremiah 8:8: "How can you say, 'We are wise, for we have the law of the Lord,' when actually the lying pen of the scribes has handled it falsely?" However, I affirm what Allah says of the early Jews in al-Qur'an 5:13, which reads, "They change the words from their places and have abandoned a good part of the Message that was sent to them. And you will not cease to discover deceit in them, except a few of them. But forgive them, and overlook (their misdeeds). Verily, Allah loves Al-Muhsinun (good-doers)."

An approximate summary of what I'm aware of about the Bible's history:

The Torah and other revelations were maintained by generations of Jews, some of whom are criticized in the Bible. scribes, some of whom, the Bible and Bible scholars, themselves, criticize, at least as regards oral law, if not the written. For example, with Amplified Bible notes added in brackets, Jeremiah 8:8 reads, "Behold, [the truth is that] the lying pen of the scribes has made the law into a lie [a mere code of ceremonial observances]." Considering this description of a sopher, though, it's unclear to me why the oral law would be connected with scribes, versus rabbis. Or, rather, why the versus isn't referring to the object scribes maintain.
The books of Moses, quite famously, include the story of his death and epilogue, but without attribution to anyone else. This, alone, isn't enough to suggest none of the Pentateuch have origin in the prophet so central, of course, to Judaism, but also Christianity and even Islam. And, of course, scholars have written and spoken on the matter, but I'm not well studied on that.
The Old Testament includes stories that depict prophets committing major sins. Again, peace be upon all the prophets. But to illustrate, a section of 2 Samuel alleges that David purposefully got a man killed in battle so he could fornicate with the man's wife. In the same book, plus 1 Kings, it says Solomon was also an adulterer. Lot, it says, slept with both his daughters, who had gotten him drunk. If any of those things had happened, there are sort of rationalizations to form. But another perspective would be that these are insertions to lower the moral bar and weaken the example of noble character of all the prophets.
As for Moses, Exodus 2:11-15 says, "One day, after Moses had grown [into adulthood], it happened that he went to his countrymen and looked [with compassion] at their hard labors; and he saw an Egyptian beating a Hebrew, one of his countrymen. 12 He turned to look around, and seeing no one, he killed the Egyptian and hid him in the sand. 13 He went out the next day and saw two Hebrew men fighting with each other; and he said to the aggressor, “Why are you striking your friend?” 14 But the man said, “Who made you a prince and a judge over us? Do you intend to kill me as you killed the Egyptian?” Then Moses was afraid and said, “Certainly this incident is known." The same story appears in Islamic texts but says Moses immediately repented. It's in Surah al-Qasas, where it reads, "And he entered the city at a time when its people were not aware [of his presence], and found therein two men fighting: one was from his party and the other was from his enemies. When the one who was his follower saw Moses, he cried out to him for help against the one who was from his enemies. So Moses struck him with his fist and killed him. Then Moses said, 'This is Satan's deed; surely he is an open enemy who leads astray. My Lord! I surely have been unjust to myself; therefore forgive me.' So God forgave him; He is the Forgiving, the Merciful."
27–29 ce, Jesus, who had grown up a Jew, delivered a message, the core of which was aimed at other Jews. He did not lead forth a nation as they'd hoped. Some Prophets are followed by many as a powerful nation and others deliver a message that may only be accepted by a few. The words or story of what he came with Jesus is known as gospel, or in Arabic injeel.
Jews tried to kill Jesus, they hated his message so much. He did not lead forth a nation as they'd hoped, perhaps misunderstanding prophesies like Deuteronomy 18:18-19 and many others.
Christian communities formed in the decades and centuries after Jesus ascended. They had texts that included gospel information. I don't know a lot about that period and I'm not sure who even does, though someone may. I don't know.
Early Roman Catholics canonized a creed and New Testament, mostly 3rd and 4th century, which formed the basis Roman Catholicism
The New Catholic Encyclopedia states that the Trinity "was the product of 3 centuries of doctrinal development."
Early 16th century Protestantism came with refreshed Bible translation from the early fragments and proliferation with the printing press. I feel like there was also an idea of return to the original Christianity, but it was via the Bible. Something like that.
The aforementioned fragments the modern Bible versions are translated from (when it's not each other) include ~3200 Greek manuscripts, ~8000 Latin manuscripts, and ~1000 in ten other languages.
As few as one verse of the New Testament is translated from Aramaic, a likely language of Jesus. Nor is much from Hebrew, the other possible language Jesus spoke. That said, one argument that Matthew wrote the gospel bearing his name is that another Jew had written it based on Matthew's Aramaic. In that sense, the non-Aramaic fragments modern Bibles are translated from may have been a translation of Aramaic. And that would be true for any red letter versus, presumably (or Hebrew, if not Aramaic).
Much of the New Testament was written by Paul who never physically met Jesus, but says he saw Jesus in a dream.

Notes (will revise soon, God willing)

Allah created Adam from soil and water and put a soul into his adult form. Eve from a just a male. Jesus he created from just a female. Us from male and female, the most common permutation. And, yet, none of us are divine at all.
Moses spit the Red Sea. Muhammad split the moon. Saleh brought a camel out of a rock. Miracles are so people can recognize a prophet and as an evidence against them if they deny what Allah showed them.
Jesus fasted for 40 days. I fast 30 days a month. It's just a misunderstanding about what fasting means, as far as I can tell. The whole Bible, actually, has wudu and salah all through it, including places where Jesus prays the way I pray, as far as I can tell.

More (will revise soon, God willing)

Many verses in the Bible at least colloquially refer to Jesus as a prophet, whereas the "son of man" and "son of God" are among the most recognized among late insertions that aren't native to the Bible.
The verse that mentions the father, the son and the Holy Ghost is of the most suspect versus in the Bible and some versions have pulled it out and then put it back in.
In Revelation 22:9 Jesus says, "No, don’t worship me. I am a servant of God, just like you and your brothers the prophets, as well as all who obey what is written in this book. Worship only God!" That's exactly what it says in al-Qur'an, and it's actually Jesus's message because Allah says He will ask Jesus if he had told the people to worship himself, and he'll say, "And ˹on Judgment Day˺ Allah will say, “O Jesus, son of Mary! Did you ever ask the people to worship you and your mother as gods besides Allah?” He will answer, “Glory be to You! How could I ever say what I had no right to say? If I had said such a thing, you would have certainly known it. You know what is ˹hidden˺ within me, but I do not know what is within You. Indeed, You ˹alone˺ are the Knower of all unseen."

There is a prophecy in the Bible of a prophet to come that would be like Moses (Deuteronomy 18:18-19), who did lead a nation, for example. Some have and do say Muhammad of the 7th century is the fulfillment of that prophecy. Peace on all the prophets. It partly depends on how a person interprets the word "from your brothers." Does that mean from among the followers of Moses, like each other, since that's who the verse is talking to? Or could it means something more inclusive? Muhammad is from among the decedents of Ismail, the brother of their ancestor Isaac. The Bible says Joseph was a descendent of Isaac, but it's unclear to me what that means for his lineage since the Bible says Jesus is born of a virgin. Regardless, the prophecy says the prophet