In and out of Christ represent two worlds -- the world of heaven and the world of hell, the world of creation and the world of decay, the world of life and the world of death.
Take, for example, the disciples: As long as they stayed in Christ, obeyed His will, caught His ways, and showed His spirit they were happy, constructive, and creative. The moment they stepped out of Him even in thought and attitude they became unhappy, destructive, and non-creative. They departed from His spirit and began to quarrel over first places -- immediately they were unhappy, destructive, and fruitless. They forbade other disciples to cast out demons because "they followed not us," and immediately faces, life, and work were clouded. They asked for permission to call down fire from heaven to consume Samaritans, and lo, relationships with themselves and others were as black as midnight. Later other disciples preached the gospel of love and redemption to those same Samaritans and lo, "there was much joy in that city."
Peter, walking with Jesus and catching His spirit, was an exuberant, creative man; but Peter, succumbing to the hard pressure, denied he had ever known Him. Result? "He went out and wept bitterly." Judas was the trusted treasurer of the most significant movement of the world, but Judas stepping out of that trust into treachery "went and hanged himself." A prominent pastor of a great city church was creative, helping innumerable people into new life through his preaching and especially his personal counseling. He stepped out of that great church, turned his back on his lovely wife and children, and disappeared with a young woman. He reappeared months later as a seller of cemetery lots in a distant city. When his landlady unlocked his apartment in his absence she found nine empty vodka bottles. In Christ he was constructive and creative; out of Christ, selling cemetery lots (suggestive!) and taking refuge from himself in vodka!