Keen was converted in Akron, Ohio, in 1958 and graduated from Bible college in 1964, at which time he and his family moved to Milford, Ohio, where he spent the next thirty-five years pastoring the First Baptist Church. In 1999, he resigned as pastor and went into missions work, primarily in the area of supplying Scriptures for missionaries in the mother tongue of the unreached people groups.

He has written three books: They Are Still Waiting, Thinking Outside the Box, and He Is Worthy. God has used him in conference work both in America and other nations.

The Keens reside is in Milford, Ohio, and they have four children.