Yes, there are many belief systems all over the planet, and you are free to accept whichever one you like. But only Christianity leads you directly to Jesus and his Word, which is the only way to the Father. Jesus' Word is the entire Bible, which is inspired of God and given to us for our Salvations. We cannot pick and choose which parts of scripture we want to accept and ignore the rest; we must accept the whole thing just as it was inspired by God. You can even pick a different god if you wish but there will come a time when you will wish you had picked the real God.
I've never found any real differences between one Bible and the next. Protestants do omit certain books and parts of books from their Bibles which the Catholics have retained; but Catholics recognize that Protestants have retained the basics needed for Salvation. In other words, Protestant Bibles are complete enough. There are off-base Protestant Bibles which are changed, such as the Jehovah Witness bibles, and they are NOT dependable.
What Paul teaches is exactly what Jesus teaches because Paul is inspired by God in his teachings.
The entire Bible is inspired of God and given to Christians for their Salvations. Christians are free to omit parts of scripture if they wish to DISOBEY God but they will have omitted things God wanted them to have. Paul does NOT teach differently than Jesus because he is inspired by Jesus.