Apostasy, or falling away from the faith as Demas did, is subtle and borne on the wings of false doctrines. Don't entertain false doctrines, which leads to heresy and apostasy and eventually, atheism. If you are truly saved, nothing can snatch you from the hand of Jesus, but don't drift away. If you are unsure of your faith, test yourself to see if you are in it, and repent unto salvation. If you are saved, stay close to Jesus in these turbulent times. It's the only safe place to be. You do not want to be that baby gazelle lingering behind the pack that's moved on when there are lions roaming up and down upon the earth.