Example, one book teaches must be keeping Sabbath, commandments, etc, and those who have left them have been lead astray.
Another book teaches that most of those things were never commanded, only that justice and good to fellow man was what was wanted.
One teaches that our time on earth NOW is it. (may or may not be an afterlife) but our earthly time should be just enjoying ourselves and being good people. That working, preaching, anything is a waste.
Another that we should sacrifice all we enjoy, not pursue any pleasures, because by going beyond all of this, there is a greater reward and greater eternal benefit.
In myself to really understand and get past the confusion of the books of the bible, each one in context, atleast on the 'face value' group them. Because either A. Some 'bad intent' deception got mixed into them. or B. There is a meaning and understanding, or history for the differences. One thing is clear, if your told something is good, then told it's bad, until you understand why or if they are from different sources will you ever find the answer.