Have you ever seen a Christian let bad habits slip in—and then after a while they're just totally gone? CS Lewis said, "The safest road to hell is the gradual one - the gentle slope, soft underfoot, without sudden turnings, without milestones, without signposts"
It's rare that a Christian just plummets away from Christ. Instead, it's usually gradual. Often their fellow Christians don't even risk confronting the sin, being scared to lose a friend or to cause offense. Heb 2:1 and 1 Thess 5:21-22 say in part, "we must pay much closer attention to what we have heard, so that we do not drift away from it," and "examine everything carefully; hold fast to that which is good; abstain from every form of evil. (1 Thess 5:21-22)
Let's pay close attention to what we've heard, and remember that part of what we've heard is that we need to keep out brothers and sisters from stumbling off alone into the darkness. Be there for them, even if it's tough.
"For the entire Law is fulfilled in in this one word: "You shall love your neighbor as yourself."—Gal 5:14