God patterned marriage purposefully after the relationship between His Son and the church, which He planned from eternity. And therefore marriage is a mystery; it contains and conceals a meaning far greater than what we see on the outside. What God has joined together in marriage is to be a reflection of the union between the Son of God and His bride the church. Those of us who are married need to ponder again and again how mysterious and wonderful it is that we are granted by God the privilege to image forth stupendous divine realities infinitely bigger and greater than ourselves.
John Piper