A Christian remains strong & unconquerable as long as he lives in full obedience to God’s word & continues in righteousness.
But the moment he begins to flirt with sin, take God’s grace for granted, & neglect fellowship & prayers of God’s people, he becomes weak & open to defeat.
Those who persist in evil while hoping that they would get away with it, should learn from the life of Saul that irrespective of how long it takes, God will never overlook sin.