The highway to hell is paved with morality as much as with decadence. Tim Keller writes about the deceptive evil of embracing Jesus merely as a model and not as a Savior:

That, ironically, is a rejection of the gospel of Jesus. It is a Christianized form of religion. It is possible to avoid Jesus as Savior as much by keeping all the Biblical rules as by breaking them. Both religion (in which you build your identity on your moral achievements) and irreligion (in which you build your identity on some other secular pursuit or relationship) are, ultimately, spiritually identical courses to take. Both are “sin.” Self-salvation through good works may produce a great deal of moral behavior in your life, but inside you are filled with self-righteousness, cruelty, and bigotry, and you are miserable. You are always comparing yourself to other people, and you are never sure you are being good enough. You cannot, therefore, deal with your hideousness and self-absorption through the moral law, by trying to be a good person through an act of the will. You need a complete transformation of the very motives of your heart. (”The Reason for God,” 177)