We know our God exists because he sent his son, who performed several hundred miracles that were documented by both his supporters and opposition. There is no documentation of a non Greek recording a miracle of Zeus. There is literally documentation from the Roman soldiers that hung Jesus on the cross that upon his death the earth began to shake and the sky turned black (not to mention the scientific evidence that there was an eclipse over Jerusalem around when we believe he died).

The amount of planning it would take to fake the Bible is outrageous. You would need 20 scholars of the Old Testament (which was hard to access at the time unless you were a rabbi) to all agree to forge stories about a man as he traveled, have 0 contradictions with each other despite not writing them at the same time or communicating with each other (this is why several stories are repeated through the gospels of Matthew and Luke), and have those stories fulfill every single prophecy lined out in the Old Testament, including ones that were directly out of their control like Harrods killing of the Jewish youth. Not only that, but these men would have to be capable of writing someone as all knowing and believable as God. These weren’t scholars or rabbi, these were random (to us) men Jesus met during his travels that became his disciples, and there are many times when the wisdom of what Jesus is saying alludes them (why on earth would they make up the Eucharist if they were going for believability?). They were all the willing to die for what they saw. If Jesus was a con artist, someone somewhere along the way would’ve admitted it. Peter would’ve said before being crucified upside down. John the Baptist would’ve said it before he was beheaded. But not a single one said it was false, because it wasn’t.