The point of preaching the moral Law to the sinner is to bring about the knowledge of sin. Modern evangelism all too often leaves out sin and judgement in place of a feel-good message that's more of a life enhancement program for this life,than a preparation for an eternity in the next. See the quote below by Charles Spurgeon.
"God never clothes men until He has first stripped them, nor does He quicken them by the gospel till first they are slain by the Law. When you meet
with persons in whom there is no trace of conviction of sin, you may be quite sure that they have not been wrought upon by the Holy Spirit; for 'when He is come, He will reprove the world of sin, and of righteousness, and of