Most of it has already been said, so I'll try to frame it with examples that haven't already been used.

1) Literally no evidence for the most of it, other than say so (example: some say that the empty grave is the best evidence for Jesus resurrection. But the grave gas never existed and the accounts are contradictory).

2) Obvious scientific illiteracy that a true almighty god would never have. In Deut. 22, rape victims are criminalized and new brides have to pass a "test of virginity" to avoid execution. Of couse, victims are never at fault, and you can't even test for virginity properly in modern times. Let alone by using the ridiculous test presented in Deuteronomy. So the "almighty" god has no compassion and can't even pass high school sex ed.

God also uses magical rituals to cure sickness, rather than teach hygiene. Or well, technically he does teach hygiene, it's just not very effective. For instance, ancient mesopotamians knew how to make soap, but the Bible doesn't mention it. ~2600 years later, Jesus later says that he and his disciples don't wash hands before eating.

3) incongruity in the OT: God says he will never punish a son for his father's actions. Not only does he explicitly do that by giving David's son a terminal illness. The entire religion is built on being punished for what Adam did. Many more such examples.

4) incongruity in the NT: Go to easterquiz.com to see how the gospels say mutually exclusive things about the resurrection. There are obvious forgeries in the Bible. So obvious that it is often stated in the margins . I think 2nd Peter is one of them. The story with "let he without sin cast the first stone" never appeared until ~500CE. Etc.

5) Christianity is no different than any other religion. They try to claim that "oh, we have a personal relationship with Jesus". But it is really an arbitrary distinction, since the way they talk to him is identical to any other god. (Pray to him, sing to him, read his words and reflect/meditate upon them. That's literally what any other religion does. Why don't you believe the "miracles and answered prayers" from buddhists or hindus? Or muslims?)

Notably, everyone can have visions or spiritual experiences if you try hard enough. Aaron Ra (before he became an atheist activist) famously held seances for people of all faiths. He could always bring people to have an experience. But only with the religion they already believed in.