Dr. John Gerstner was a theologian of the highest quality. He was the mentor of R. C. Sproul and even if he had never written one book this would secure him a place in all of our hearts.
Even though I never had the privilege of hearing or meeting Dr. Gerstner in person, he has also influenced me through his collective 'Primers'. These are available in one volume, titled, Primitive Theology, from Soli Deo Gloria Publications, now a part of Ligonier Ministries.
Here is Dr. Gerstner's Testimony in his own words.
I was born in 1914 of a mother who was a Methodist, in the sense that it was the Methodist church that she stayed away from. My father was a Lutheran, in the sense that it was the Lutheran church from which he stayed away. Mother was casual, but father saw to it that I washed behind my ears. Neither had religious concerns for themselves or for me. Consequently they were surprised-pleasantly-when little Johnny got interested in the ministry.
That interest came through a girl I went with my senior year in high school. There was a minister in the United Presbyterian Church of North America (UPNA) I attended with her who, though he may have been thin in his theology, was quite determined to see that I, with ten dollars in my pocket got off to Westminster College (PA) in 1932. A high school teacher, the president of the college, and the Overlook Sanitarium (which gave me a job for room and board) helped me meet my expenses.
Before going to Westminster College I had one of the two most definitive experiences of my life. First, Philadelphia School of the Bible made me, for the first time, aware of the "crimson thread"-the theme of the blood of Christ-running through the Bible. The second definitive experience was when Professor John Orr, during my second year of college, said in a class that "regeneration precedes faith." When I came out of my Arminian trauma three weeks later, I was, and have remained to this day, a Reformed person, minister, and historical theologian.
I have reason to hope that the heavenly Father has had saving mercy on the otherwise hell-bound sinner before you. (Taken from: John H. Gerstner: The Early Writings Volume One. Morgan PA: Soli Deo Gloria Publications, 1997)