Origin of Unclean Spirits & Possession:

[TJJJ]

I see a lot different than this.

If spirits could go out and have relations with a woman back then, then they could do that today! Brother, this is very similar to serpent seed doctrine. We don't see that going on today do we?

This doctrine you are suggesting was and is very popular with the Charismatic movement that came out of the latter rain movement.

To say that all of these giants/half devils died during the flood. Where did the giants come from that Israel fought, then about a man named Goliath?

I agree that unclean spirits look for vessels to use, but the origin issue has some flaws.