You're right:  I was raised Presbyterian and I became a Roman Catholic when I was 29 years old.  Here's the story.

I grew up on the North Side in Pittsburgh, Pa.  On our "block" (from one corner to another) we had 78 kids!  It was a blue-collar, steel-working neighborhood.  Nearly everyone went to the Brighton Road Presbyterian Church at the top of the street, or St. Cyril of Alexandria's Catholic Church on the block behind us.  The Catholics outnumbered the Presbyterians, and those who went to St. Cyril's elementary school got more days off than those of us who went to John Morrow public school!

In our church, my father was an elder and my mother was a deacon.  Life really centered on the church:  Sunday school and church on Sunday; youth group on Wednesday; dances on Friday; and Camp Crestview in the summer.  It was a very nice way to grow up.  When I graduated from public high school I joined the Marine Corps, 1966-1972.  When I left home I also left the church.  No particular reason; my life just took a different turn.

Once I left the Marine Corps I started college.  I was a 24-year old freshman with 6 years of Marine Corps experiences behind me. I had a lot of questions about life that needed to be answered.  I became an English/Philosophy major.  My studies became my great joy, and the more I read, the deeper I probed the big questions of life.

I graduated summa cum laude and started a Master's degree program in English.  My search continued.  During that time I met a very fine English professor, Dr. Jack Evans.  He became my mentor and friend.  I recall visiting his office one afternoon and saying, "Dr. Evans, I feel like God has unleashed the 'hound of heaven' on me."  Jack is one of the best men I have ever known, and he is a devout Roman Catholic.  He said to me, "Bill, there are a couple of books you should read:  C.S. Lewis's Surprised by Joy and Thomas Merton's Seven Storey Mountain.  Both Lewis and Merton wrote their books in their 20s and both describe their search for God.  I read them, and I discovered kindred spirits.

I was drawn back to God by Jack Evans and those two books.  I continued reading and studying:  Augustine, Aquinas, Thomas a Kempis, St. John of the Cross, Calvin, Luther.  And I became entranced by 17th century metaphysical poetry:  John Donne, George Herbert, Andrew Marvell, Thomas Traherne, Henry Vaughan, Richard Crashaw.  The more I studied the more I came to appreciate the beauty of the church, of Medieval and Renaissance religious art and music, of liturgy.  For me, they all expressed the depth and breadth of God's love, of his infinite capacity for beauty.  

To make a long story short, I was drawn to the Roman Catholic church.  My studies and the living example of Jack Evans' life brought me home.  Jack and I have been friends for forty years now, and he is still the best man I have ever known.

In a very personal sense, Logos Bible Study is an expression of my faith expressing itself in love.  LBS is not a Roman Catholic endeavor; it is a Christian endeavor.  Our students are about half Catholic and half Protestant.  Our live venues are equally Catholic and Protestant.  I strive mightily in my teaching and my life to rise above denominational issues and simply to teach and live the Word of God.  I think I do a pretty good job of it most of the time.  Christianity is not about dogma, theology and denominations; it is about living an intimate, personal relationship with God through Christ.

C.S. Lewis said that his job was to get people into the house (the Church), not to determine what room they would live in (denomination).  I try to do the same and to encourage all those living in the family.  

I hope that answers your question.  It's not something I typically address, for it usually leads to division, rather than unity.  But you asked, so there it is.