" The Lord’s second insight goes deeper than the obvious. Indeed, it is amazing. Jesus read the perhaps ambiguous word “become” in “they shall become one flesh,” and he saw something there that we might never have thought of. Behind the word “become” Jesus sees a personal power at work. He sees no one less than God: “What therefore God has joined together . . .” (v. 6). A husband and wife, when they marry, do not become one flesh by their own wills or by the pastor’s pronouncement or by some mysterious process. God joins them together (Mal. 2:14–15). "

― Raymond C. Ortlund Jr. , Marriage and the Mystery of the Gospel (Short Studies in Biblical Theology)