I’m not sure I completely understand what you mean, but I would be concerned about a church that brought you into any kind of leadership role without even being a member.
I say this as someone who is joining a PCA church in the coming months. And hoping to becoming a pastor (in 5-10 years).
While I can't speak for
@Dpatt2033 (Darion Patterson), I do think there may be some underlying ecclesiological issues here that can lead to honest misunderstandings between traditionally Reformed people (i.e., the NAPARC world and related denominations) and people who are from a non-Reformed background and have become theologically Reformed, but have not seen how Reformed church government works, or at least is supposed to work, in actual practice.
Church membership matters in the Presbyterian and Dutch Reformed world. It is supposed to matter in the Reformed Baptist world, and to their credit, it often does. Same for some but not all other groups that are soteriologically Reformed. I realize there is a lot more variation in the Presbyterian world on what a local church can do with pulpit supply, but the Dutch Reformed denominations often have rules that say people who are not ordained can only fill a pulpit under certain conditions such as having been "licensed to exhort" by the denomination following an examination by a classis or consistory, depending on the specific denomination, which for seminarians usually happens only after completing the first year of seminary. Rules for Presbyterian pulpit supply can vary a great deal between denominations.
That just isn't the way a lot of American evangelicalism works.
In a lot of evangelical circles, it is not just allowed but common for a man to go to seminary, look at a list maintained by the field education office of churches seeking pulpit supply, interns, and people in assistant pastor roles, and send applications. What local church or denomination a seminarian belongs to may not make a lot of difference if the church seeking pulpit supply, a paid intern, or even an assistant pastor likes the man.
In the NAPARC world, it's not unheard of for a person who is a member in good standing and has received proper licensure (or other authorization to preach) to serve in a different NAPARC denomination. This is not new -- even way back in the 1980s, I knew a man in one of the more conservative NAPARC denominations who was studying at RTS-Jackson and spent a lot of his time preaching in PCA churches because his own denomination had very few churches in the South. I personally have been invited to fill a lot of very conservative NAPARC pulpits, but I'm probably a special case because back in the 1990s I was pretty well known in a lot of places that normally would never let a person from my ecclesiastical background fill their pulpits.
In those cases, church membership still counts, but it's one NAPARC church recognizing the church membership and licensure decision of another NAPARC church, or of a non-NAPARC church that is regarded as being sound and whose elders have made decisions that can be trusted.
What Darion is talking about is different.
If I understand his situation correctly -- and please correct me, Darion, if I'm wrong -- he's from a Baptist or baptistic background, attending a non-Reformed seminary, has become theologically Reformed, and since he wants to join a local OPC or PCA church, I assume he is now not only confessionally Reformed but now also believes in infant baptism, so he can't subscribe any longer to the 1689 Second London Baptist Confession.
That means if he's currently a member of a Baptist or baptistic church, it would be entirely reasonable and legitimate for the church where he is a member to say, "You are no longer in agreement with us, doctrinally, on baptism (and perhaps on other things) and we can no longer endorse you to preach in churches, but we will happily transfer you to a Reformed church that practices infant baptism." That's the best-case scenario with a Reformed Baptist church that recognizes the PCA and OPC as brothers in a shared faith. Sadly, a lot of Baptist and baptistic churches outside the Reformed Baptist world might not be as cooperative with a member who no longer believes a core part of being Baptist, i.e., believers baptism. I've seen bad things happen when people change their views on baptism
What Darion is doing is not as simple as an OPC man transferring to a PCA, or even transferring from a Presbyterian church that holds to the Westminster Standards and joining a Dutch Reformed denomination that holds to the Three Forms of Unity. The confessions are different but they're close.
Baptism is not a minor matter. It's not the most important thing -- I have a decades-long history of saying that Reformed Baptists are brothers in the Reformed faith -- but because baptistic views often indicate significant differences on covenant theology or even (in the case of MacArthur people) a dispensational or semi-dispensational position, a seminarian from a baptistic background seeking to join a NAPARC denomination should have a REALLY serious examination before being allowed to teach or lead anything, and unless the man is personally known to the elders, most of the time that means significant time as a private member to observe his doctrine and life.