According to God’s Word, tolerance is as great a sin as the actual act. There have been times when I have witnessed to a person who was outwardly very kind and upright. When I’ve used the Ten Commandments to show them their need for the Savior, they have denied harboring hate, ever lying, ever looking with lust, ever taking the Lord’s name in vain, or ever being greedy. Of course they are deceived, but how do you continue to warn the very self-righteous?
One way is to explain the spirit of the moral law by proving that sins of omission are also violations of God’s Holy Law. For example, if they are not grieved over, nor shun, all the lust and perversion being broadcast, they are guilty of fornication by association. If they say they are personally against abortion, but would never reprove those who are pro-abortion, then they are tolerating murder. If they endorse pro-abortion candidates, explain to them that in God’s eyes this is no different then if they were to endorse Hitler’s regime. You can’t be pro Hitler, but anti-holocaust. Winking at wickedness offends God.
As you study the Word of God to learn the spirit of His perfect Law, use it to warn those who have a false assurance in their own righteousness.