You asked a question that indicates whether or not the possibility exists that a Christian, entertaining a hope of eternal life, could sin, and once again become guilty before God. Scripture clearly represents that as a distinct possibility if not probability. “If any man sins.” There is no ‘cause,’ other than ones own will, than forces that to happen, but it most certainly can and does happen. I believe any notion to the contrary, will of a certainty, run the risk of one closing their eyes to the real distinct possibility of displeasing God with their intents, and run the risk of self-deception as to their standing before God, and lead to a false definition in ones life as to what sin is and the consequences of it. No amount of doctrinal belief to the contrary can wash ones hands or purify ones heart before God. Only as we as believers are willing to face and confront our sins, as wicked and selfish as they might be, and to seek forgiveness via repentance and faith, can we maintain our standing before the Lord and our sure hope of eternal life with Christ.