Simply put, it does not provide answers for sinners.
I am a sinner. In my prison ministry, I minister to those who even the most liberal in TEC would consider sinners. Without Jesus paying the price for our sins, sinners have no hope. In their desire to eliminate inconvenient sins and belief in things the post-modern world finds difficult to believe, liberal Christianity simply guts the faith and makes it useless for sinners.
I wonder if it is useful for anyone.
Christianity is for people who are willing to admit their guilt and receive forgiveness. Otherwise, it is a waste of time.