In my opinion, Satan's works does not hit the innocent mind first, the Evil gets into the consciousness of people with power, it attracts it, and those people with power do his work for him, bending moral codes, bending behavioral codes which were placed there by God. How does the door open? Look to the 7 deadly sins. Like a rat, the opening does not have to be that large, just an inch. Didn't Satan come for the Son of God himself? Yes. He entered Judas through money and jealousy, he enters through entertainment and sexual seduction, he enters through Pride. Do not leave a nesting place for him. Keeping rats out of the barn is a constant practice, think of yourself as a barn, close up the holes, keep it clean, it's a daily chore, not something you want to let go until you have time for it. Pray daily, avoid temptation, stop preening in pride, stay humble, Satan wants nothing to do with humble people, it repels him . The world has been full of these sins, they have just "trickled down " to the masses enough so that we are all aware of abominations that have been going on since Cain slew Abel. The internet itself is his tool, be aware of that.