William J. Mencarow Jr. (date of birth unknown – ) is an American preacher, Reformed pastor, and author whose ministry blends a deep commitment to biblical theology with a diverse background in politics and finance. Born in the United States—likely in the mid-20th century, given his career timeline—Mencarow grew up in a non-Christian home, working as a Capitol Hill staffer and Reagan administration aide, where he served as Minority Counsel and Staff Director for the U.S. House Subcommittee on Government Operations. Converted later in life through immersion in Scripture, he married Alison, his lifelong partner, and wrestled with a call to ministry—likening it to Jacob’s struggle in Genesis 32—before apprenticing under Rev. Robert Schoof, a Westminster Seminary graduate, and studying at Whitefield Seminary. Ordained in the Presbyterian Church in America (PCA), he pastored Reformation Church in Boerne, Texas, near San Antonio. Mencarow’s preaching career centers on expository sermons rooted in historic Reformed theology, with over 300 recorded messages on SermonAudio addressing topics like Revelation, worship, and God’s sovereignty—his series on Revelation earning praise for its historical accuracy and theological depth. Known for a robust, no-nonsense style, he’s preached at Washington Reformed Presbyterian Church and other venues, advocating the regulative principle and critiquing modern church trends. Beyond the pulpit, he co-founded The Paper Source Journal with Alison, leveraging his expertise as a note investor since 1981, and authored books like Back to the Future: History Written in Advance (2020), unpacking biblical prophecy. His media presence spans Good Morning America, The Wall Street Journal, and FOX News, reflecting his earlier Washington, D.C., career managing political campaigns.