If you or someone you know has fallen into sexual immorality, and they claim to be a believer, warn them that the unrepentant sexually immoral will not inherit the kingdom (1st Cor 6:9). The Apostle Paul warns us all, and for good reason, “Flee from sexual immorality. Every other sin a person commits is outside the body, but the sexually immoral person sins against his own body” (1st Cor 6:10). God may have to use you to warn them for their own good, and you might even need some help (Matt 18:15-20), but help them you must! You may have to even tell them, out of love, that “you may be sure of this, that everyone who is sexually immoral or impure, or who is covetous (that is, an idolater), has no inheritance in the kingdom of Christ and God” (Eph 5:5).
