I have always understood the phrase, in its original sense, to refer to romantic (or sexual) surrender, but it has also been used to refer to religious or spiritual surrender. It has appeared in numerous songs over the years: Frank Sinatra, John Denver, and Sarah Mclachlan have all deployed it.
What is its origin? I assume it might be a reference to a line of poetry? (The first use I can find, with my meager Google skills, is as the title of a 1935 film.) Anyone have the straight dope?
I don’t really know the answer, but if you look at Google Books, it’s used on a number of occasions in the 1800s to imply romantic surrender, but the references in the 1700s appear to be religious surrender.
The earlier use I can find is from John Johnson’s 1754 “The Faith of God’s Elect” which refers to the “sweet surrender of all your powers into the bosom of Christ and the will of God”
And Google ngrams shows that the phrase zoomed up in usage only in the last few years. That’s apparently tied to its popularity in romance novels.
A bit of searching found some possible proto-uses before 1754. The Poet’s Ramble after Riches; or, a night’s transactions upon the road, burlesqu’d. By E. Ward, 1698, has a line “They did so sweet a kiss surrender,” clearly romantic. It wouldn’t take much to shorten that to sweet surrender as a metaphor.
The phrase was more frequently used in 19th century poetry, also in the romantic sense, but that was 100 years after its first appearance and none of the examples appear likely as the one that put it into popular usage. More probably it was just in the air and easily plucked.