So we have Hinduism, Buddhism, Judaism, all older than Christianity.
There is Zoroastrianism too and these are just some of the older religions that are still practised.
Sumerian religion is no longer practised but many of its stories are newer religions so perhaps is still relevant.
That goes back to 5000 bce and prehistory.
Never mind, Christianity seems to be older than Islam, not that that fact makes it any more valid.
The mistake you make is to think that Christianity started at 0 b.c. I can understand why you might think that and in a sense it's true, that's when followers of Christ started to be called Christians. The fundamental belief of Christians is that the only way to heaven is through a saviour. That's the message of the old testament from start to finish. The Jewish people in the Old Testament were being taught this by God. So Christianity has its roots firmly in Genesis.
Hinduism and Buddhism come well after earliest Biblical history.