If what we are hearing in some circles, the answer would be: "Whenever the subject of grace
enters the picture."
You probably thought that you have to be baptized in order to be saved, since that is what the Son of God said, along with the inspired writers who wrote the Bible (Mark 16:16; Acts 2:38; 22:16; 1 Pet. 3:21). But now we are being told that to teach the essentiality of baptism for salvation is to be legalistic even though the Bible teaches it.
You also probably thought that repentance is necessary for salvation, since that is what Christ taught (Luke 13:3, 5; Acts 17:30-31). But supposedly only self-righteous people now teach that, because grace covers all our mistakes.
Perhaps you also thought that faith is absolutely demanded of mankind in order to be saved (John 8:24; Heb. 11:6), but even faith is a work (John 6:29), and that would bring us back to the legalistic charge being hurled once again! However, since the works that God demands of us are not the meritorious works of men, then we are still obligated to work the works of God.
No, we cannot earn our salvation, but doing what God says is not earning salvation. It is loving the Lord (John 14:16; Luke 6:46). Since Paul taught that we are not to "continue in sin, that grace may abound?" (Rom. 6:1-2), we better just keep on trying to obey God, truly relying upon the grace of God, instead of accepting man's perverted version of a cheap grace that makes no demands (Titus 2:11-12). Cheap grace ultimately leads to universalism!