Only Begotten God
Turn to John 1:18 in your bible. Chances are, your Bible has a passage like this one in the King James Bible:
No man hath seen God at any time; the only begotten Son, which is in the bosom of the Father, he hath declared him. John 1:18, KJV
The New American Standard Bible has a surprising difference:
No one has seen God at any time; the only begotten God who is in the bosom of the Father, He has explained Him. John 1:18, NASB
Other Bible translations also render this passage as "begotten God".
Christian apologists explain that Jesus always existed as God and that in keeping with the tenets of Jewish monotheism, Jesus and the Father are one and the same God. Jesus was begotten only "in the flesh" (corporally), not spiritually. Jesus is God himself incarnate
But Jesus begotten as God means that Jesus isn't an eternal deity. It means that the God, Jesus, had a beginning in time.
Why are there Different Translations?
The reason different Bible translations exist is that the translators used different sources. Some used older sources which were more like the originals. Others used more recent sources that were copies of copies of copies of the originals, each copy adding more changes to the previous copy.
Some changes from copy to copy were intentional edits. Scribe changed passages that conflicted with their personal theological understanding. Other changes were mistakes. Scribes accidentally added or omitted letters, substituted similar sounding and similar looking letters, and transposed letters, in each case resulting in different words. Scribes promoted margin notes to bona-fide scripture. That is, scribes incorrectly thought that notes written in the margins of the manuscripts they were copying were corrections to the scripture rather than just notes.
Which Translation is Correct?
The original Gospel of John was written some time between 90 CE and 120 CE. The oldest Greek manuscripts we have that contain the Gospel of John, like Papyrus 66 written around 200 CE, and Papyrus 75 written between 175-225 CE, record John 1:18 as "begotten God".
The first manuscripts that have "begotten Son" in John 1:18 are centuries older than manuscripts that have "begotten God".
The original text of John 1:18 almost certainly said "begotten God".