Typically this is a Christian argument used against Islam - but I’m actually curious if this is seen as a valid argument from a secular point of view? (Even if it’s not the “best”)
Because essentially it’s “your holy book contradicts the holy book it claims to be endorsed by”, which personally I think I can see working on a secular level, even if you don’t actually believe in the Bible either.
spoiler
! Also, full disclosure: Yes, I am a Christian. !<
Ironically this means you’d have to accept Jewish people telling you that the New Testament isn’t canon also.