A healthy body is self healing; if you are cut or wounded your body goes to work at healing itself. The fellowship of believers should also be self healing; if a member is hurting we all should reach out and seek to comfort and assist in healing the broken and bruised. In James 5:19 we read: Brethren, if anyone among you wanders from the truth, and someone turns him back, let him know that he who turns a sinner from the error of his way will save a soul from death and cover a multitude of sins. (James 5:19-20 NKJV)
In our post-modern culture we tend to stand alone, a bit out of reach and out of touch. It is possible to be hurting and no one else knows; or to sit with and even be friendly with another believer without ever knowing their pain. Our western mindset is live and let live, so if a brother or sister wanders from the truth: it is easy to let them go, not bother with them, write them off, not trouble ourselves. But if we do reach out and gather in the wandering: bring correction to error, to retrieve the one seduced by sin or false doctrine; it is possible to save that soul from death and their sins will be forgiven.
This is the task of each of us as we care for one another, as we are concerned for our friends in Christ. Sparks might fly if you do this as iron sharpens iron. Your brother or sister in Christ who has wandered from the truth needs you to turn them back to Jesus and help them be free from the entanglements and the estrangement that will surround them. In Galatians 6:1 we read: Brethren, if a man is overtaken in any trespass, you who are spiritual restore such a one in a spirit of gentleness, considering yourself lest you also be tempted. Bear one another’s burdens, and so fulfill the law of Christ. (Galatians 6:1-2 NKJV)