Baylor University History Professor Thomas Kidd discusses the origins of the phrase "ask Jesus into your heart," which is not found anywhere in the New Testament.
Kidd points out that,
The phrase “ask Jesus into your heart” is not in the Bible, although there are similar phrases there (“ye have received Christ Jesus the Lord,” Col. 2.6 KJV). So where did this prayer come from?
It turns out that Anglo-American Puritans and evangelicals in the seventeenth and eighteenth centuries used the phrase “receive Christ into your heart,” or something like it, with some regularity. The great Puritan devotional writer John Flavel, for example, spoke of those who had heard the gospel but who would “receive not Christ into their hearts.”
But it was just as common for pastors of that era to use the phrase to describe a Christian act of devotion. Thomas Boston, a Scottish Calvinist pastor, encouraged Christians taking communion to receive “Christ into their hearts.” Benjamin Colman, the leading evangelical pastor in Boston in the early eighteenth century, wrote explicitly that Christians should “receive Christ into their hearts, and hold him forth in their lives.”
There was a time in my life when I was certain that both Jesus and Paul must have told people "to ask Jesus into their hearts" in their own attempts at personal evangelism. I hadn't thought about how confusing it would have been had Jesus himself actually told people to do this.
But I was surprised at first about Flavel and Boston using the phrase, but then realized that what they meant by "receive Christ in your heart" is not what most of our contemporaries mean when they use it as the key petition of the sinner's prayer.
To read Dr. Kidd's entire post go here, Asking Jesus into Your Heart