) What is the mystery? It is that Christ dwells in the hearts of those who have crucified the old man of sin, and that as a consequence they have a hope of eternal glory! Such is what the Lord requires of his children in working out their "own salvation with fear and trembling" before him. (Phil. 2:12.) And it is in this connection that Paul says, somewhat caustically, "But if our gospel be hid, it is hid to them that are lost." (2 Cor. 4:3.)