What God has joined together let no man put asunder

What's the meaning of the phrase 'What God has joined together let no man put asunder'?

The part of the Christian marriage ceremony that states God's authority over man.

What's the origin of the phrase 'What God has joined together let no man put asunder'?

The injunction is taken from the Bible, Matthew 19:6. It appears first in print in English in Miles Covedale's Bible, 1535:

 Now are they not twayne then, but one flesh. Let not man therfore put a sunder, yt which God hath coupled together.

It is interesting to note that 'asunder' was, in the 16th century, 'a sunder'. The two words have merged into one, in the same way that many nautical terms, like 'aboard', 'amidships' etc. have done.