As for Acts 8:37 none of the most ancient manuscripts include this material. The King James Version is the one which got it wrong. You are telling here here that the King James Version of the Bible is wrong. So how can we trust the other versions of the Bible because KJV is the oldest Bible which was first English translation from the Greek manuscripts? If this is wrong how can we be sure that the other versions that came later are correct? How can we be sure that the word of God was given to us without errors when the oldest version of the Bible itself is wrong? And what about the dating of Jesus birth? If he was born between 4 to 7 BC, by the time he began his ministry wouldn’t he be 23 to 27 years old and is it not a contradiction to Bible saying he was 30 yrs old?And what about john 7:53 – 8:11 where Jesus forgives a women caught in adultery? Scholars say that this was not present in ancient manuscripts. So how can we trust the Bible if this is true? Without seeing and dating the originals can we trust them and what about other verses that we read in the Bible which are not present in ancient manuscripts but were added on later? Can’t these affect our faith in the reliability of the Bible?
Acts 8:37 is one of about a half dozen examples of what are called interpolations which are found in the King James version of the Bible, but which scholars now reject as interpolations. An interpolation is something that was probably written originally in the margin of a manuscript by a copier or one using the manuscript to explain something in the original. Then, a later copier included the addition into the text. Other examples include parts of 1 John 5:7-8 and John 5:3-4, as well as John 7:53-8:11 and Mark 16:9-20. The first three are certainly interpolations, and the last two are very likely, but not certainly interpolations. With the first three, no manuscript in the first six hundred years after Christ include them, whereas, some very early manuscripts (but the minority of them) include John 7:53-8:11 and Mark 16:9-20. Also, these two passages, unlike the first three, are quoted by Christians as early as the second century. This is an extremely short version of the evidence. You can get more in my book Reasons for Belief (www.ipibooks.com) or by doing a search of the web site.
Why are these interpolations found in the King James version? The reason is that when this translation was made in 1609 the committee which made the translation only had access to about two dozen Greek manuscripts, and all of them were from after AD 1000. All of the available manuscripts were of what is known as the Byzantine Text, which was created around AD 1000. In the last four hundred years scholars have gained access to more than six thousand Greek manuscripts, as well as very early manuscripts of Latin, Coptic and Syriac translations. Hundreds of these are from well before AD 1000. Our received Greek text of today is greatly superior to what was available to those who created the King James (and the Tyndale, the Geneva and other translations in the 1500s). Here is the bottom line, we cannot fully “trust” any translation. Only the original autographs are perfect. However, with many thousands of manuscripts, dozens of which go back to the second and third centuries, and hundreds of which go back to the first five centuries, the manuscript evidence for the Greek text is extremely good. We have a nearly perfect Greek text. With translations, none is perfect. No translation is absolutely perfect, but with good committees, with scholars form a variety of Christian groups, there are more than a dozen really excellent translations into the English. If you want to do even more careful study, you can reference the Greek text, or you can read the works of great scholars of koine Greek. We have plenty of resources, making our access to the New Testament very reliable indeed.
You wonder how we can trust the Word of God if the oldest version is wrong. Are you talking about the King James or the Greek manuscripts? If you are talking about the King James version, it definitely is not the oldest English translation. There were about a half dozen translations which preceeded the KJV, such as the Tyndale Bible and the Geneva Bible. In this case, older is not better. In fact, newer is better because scholars have uncovered thousands of manuscripts, including three entire Greek New Testaments (Vaticanus, Alexandrinus and Sinaiticus) from the fourth century, and many earlier ones as well. You can be extremely confident of your access to excellent translations, especially in English. Besides, having more than a dozen good translations allows us to compare in order to get an even more precise understanding of the original Greek.
As to the date of Jesus’ birth, it happened before Herod the Great died in 4 BC. Jesus was probably born either in 5 BC or 6 BC, but we cannot absolutely rule out 7 BC. 4 BC seems very unlikely. He was killed in AD 30 (there is some doubt about the year, but this is easily the most likely), making him about 32 when he started his ministry. I have no idea why you mention 24 to 27 years old. Maybe you did some incorrect math! ?
As for John 7:53-8:11, I already mentioned this one. Unlike the John 5 and 1 John 5 interpolations, I believe it is very highly likely that this is a genuine story from the oral history of Jesus, which may well have been in the original of John, but perhaps not in the location where it is in in most manuscripts. The story of how the account of the woman caught in adultery came into our Bibles is a very complex and fascinating one, but I am convinced that, even if it was not originally in John where it is now in most Bibles, it is a genuine story about Jesus.
Here is the thing with these interpolations. Manuscript evidence decides whether they were original or not, but no important biblical teaching is changed, whether they are included or not. If you look at the five interpolations I mention above, you will see that no theological or doctrinal thing is changed about Christianity whether these are included or not. Therefore, these questions are important and interesting, but our belief in Jesus is not affected in any significant way by these questions. You can be very confident in the New Testament picture of Jesus overall for sure.