Do atheist think Ouija boards are portals to the underworld? Or a way for demons and spirits to talk to them? ?

oh my god. yes. please don't ever mess with that ****. it isn't so much about the tangible ouija boards, but the fact that you are spiritually opening yourself up to other spirits. It's like you are telling them that you want them to be in contact with you, and possibly posess you, or at least twist your thoughts. i believe in demons with all my heart.