Sheep wander away and sometimes people do. We are to never just merely “let them go”; we are called to bring them back. Wanders may leave because they are wounded; if so, we are to offer healing. Wanders may leave because they have fallen in some error; we are to help them return to truth. In truth there is life; to return them to the fold is to save them from death. In addition, it will bring them back from a “multitude of sins”. Jesus is the Truth and Life to which we want them to return. Reach out to them in the same way you would want someone to reach out to your wayward son or daughter. Be Jesus to them; go love on them. Be sure, though, to leave your judgmental hat behind.
“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.” (James 5:19–20 ESV)