James 5:19, 20; My brothers, if anyone among you wanders from the truth and someone brings him back, let him know that whoever brings back a sinner from his wandering will save his soul from death and will cover a multitude of sins.
More proof that the believe cannot sit ideally by while is fallen brother wanders lost in a world of sin. Instead, he is to reach out to the lost sinner with love and gentleness. Knowing it is nothing of our doing, but the Holy Spirit working through us that brings the wandering soul back into the fold.
But to him that professes to be a Christian and has no concern for the lost, he will have lost his own soul to death.
The Bible In Your Hand 