Bottom line: Only God's grace can change us and give us true life.

The central question of the gospel message is, "Do you want to change?" This question is a question of desire not a question of ability. In John 5, Jesus asked the man who laid impotent for 38 years at the pool of Bethesda if he wanted to change. The man answered, "I can't." He answered the question speaking of his inability. Jesus wanted to know his desire.

The whole point of John 5 and the healing of the impotent man is that we cannot by our self effort change ourselves spiritually any more than the impotent man could change himself physically. Seeking to change ourselves spiritually by self effort to make ourselves righteous with God is legalism. We can only be changed and made righteous with God by His grace. That is what the gospel (the good news) is all about. It's not about the "do" of you. It's about the "who" of Jesus. He is the one who makes us whole, well, righteous, and gives us life eternal.