You don't know what you're talking about. The mikva is for ritual purification. Of anyone unclean. Including converts who are considered unclean because of their background. Here, here, here.
I don't have the time or interest to cover the rest for you.
Don't go making claims like that unless you're willing to back them up.
Totally different concept than baptism, other than both involving water.
Actually, there are only a few differences. We only use it for conversions (and everyone, even those with Christian parents, are considered to require conversion), not the other uses they have. And we don't require total immersion in the sense they do (not even Baptists), and some don't require it at all. The washing symbolism is superceded by death and resurrection symbolism.
Unquestioning devotion to your faith rather than rational inquiry coupled with limited knowlege blind you from being able to think rationally.
My knowledge is evidently a little less limited than yours.
Funny that you ignored the picture of the dionysus/bacchus crucifiction image...
Without context, it's meaningless.
Google and a skeptical mind are your friend. At least, they are mine.
You should have tried Googling "mikva".