I can't speak for others, but here is my story.
As I graduated from college and prepared to head off for seminary in Memphis, Tennessee, my college pastor offered a bit of advice: don't waste your time debating other students about Calvinism, he said. It will only prove confusing and will distract you from "soul winning."
While I intended to follow advice from a mentor I admired, it was partly undermined by another commitment of my upbringing, the belief that the Bible was the inerrant Word of God and required my study and allegiance. That the Bible addressed the Gospel in a more God planned, God centered way than I had previously thought required modifying my understanding of God's saving grace. I remained concerned that a belief in election and predestination would cause a loss of enthusiasm for evangelism, but I was assisted in that regard by a short book by James I. Packer called Evangelism and the Sovereignty of God. Packer argued persuasively that not only was divine sovereignty consistent with the evangelistic enterprise, but in fact it provides the only sound foundation for confident evangelism.
Because Packer was helpful to me in that book, I next read his best known work, Knowing God. That book does not deal with Calvinism as a predominant theme, but I found in Packer something I had not experienced before: a writer of serious theology that is also devotionally rich. Because I found that combination in his writing at a formative stage of my theological development, he became a key influence for me.
In addition, a Baptist committed to biblical inerrancy can't help but encounter the work of B.B. Warfield and J. Gresham Machen, two scholarly and Presbyterian advocates of biblical authority that have shaped modern evangelicalism's understanding of the Bible.
As a result of all of these influences, my doctrinal commitments began to move. While I didn't really know the doctrinal categories prior to seminary, in retrospect I can say I was moving away from prior commitments to a kind of Arminianism that bordered on semi-pelagianism toward a soteriological Calvinism. I was not there yet, but that was the direction at the time I completed my M.Div.
Some of the professors at my alma mater also held to reformed Baptist commitments, though the president of the school and many of the trustees were firmly against those ideas. Because of this, a professor who published a book on the history of the doctrines of grace in Baptist life was ultimately forced out of his job, reportedly as a result of the book's criticisms of "the invitation system." Although at that time I had not yet fully committed to a Calvinistic understanding, the professor in question was an excellent scholar and popular lecturer. I thought his views were certainly within the bounds of evangelical Baptist theology. As such, I was shocked that he had been let go. I only had a semester left before graduation -- if it had happened sooner, I likely would have transferred.
Nonetheless, this event had a profound impact on me in that it cut my sense of belonging to my alma mater. After graduation, I took a position working as a mission pastor in Pennsylvania. During that time I read a book by George Marsden, Fundamentalism and American Culture. Marsden is a first rate historian. His historical account of the rise of fundamentalism in the years 1859 through 1925 provided a grid through which I could evaluate various historical influences on my own Christian understanding. Marsden's history helped me understand that I was attempting to hold on to views that in some respects were contradictory. Working though that, I came to a better understanding of where I fit into American ecclesiastical culture.
Subsequent events in Baptist life furthered my sense of disconnectedness with my roots. As Southern Baptists increasingly became aware of a rising Calvinistic movement in their midst, numbers of them began letting us know that we were not welcome -- I actually wrote a letter to the editor of one of the state Baptist papers around 1990 complaining about the uncharitable rhetoric and later talked to a Baptist college president who expressed appreciation for my call for more constructive dialogue. That said, while I can be pretty stubborn in some ways, I have never been one to hang around when told I am not wanted.
As a result, when I left the pastorate for reasons unrelated to this topic, I decided to begin attending a confessional Presbyterian church. At the time, I still believed in believer's baptism only and was ambivalent about connectionalism, but I wanted to attend church where my growing commitments to Calvinism would not be controversial and where I could learn more about worship, a subject I felt I did not adequately understand.
My pastor at my new church, through dialogue and written materials, helped me work through questions regarding baptism, as well as a fuller understanding of covenant theology. Even so, it would not be until 2013 I would feel again called and prepared to begin the process of pursuing credentials in a Presbyterian communion (first, the PCA, then the OPC). Nonetheless, here I am, and I am thrilled with where God has brought me.
One benefit of my path is that, living in the south, with its heavy influence from Baptist and Bible churches, I have a good understanding of the beliefs and questions of those who are seeking. I enjoy working through those with anyone who wants to learn.