Doctrine matters. We should always confront the FVs on one hand and the Dispys (including MacArthur) on the other to study the purity and peace of the church.
What’s an FV?
And how do we know good doctrine? It agrees and is based on the Scriptures.
Sola Scriptura!
Let me guess, a 5-point Calvinist? I'm a 5-point Calvinist as well but I try to avoid the argumentative attitude so common among Calvinists. It has never been my contention that a person has to be a Calvinist in order to be a Christian. If perfect theology is required to be a good Christian, we all fail. I have a good friend who is a 5-point Arminian with whom I discuss theology frequently. We joke that the other is saved, he just doesn't know why. While perhaps cluttered with theological errors, the Gospel is still contained in the teachings of MacArthur, Dispensationists, Federal Visionists. As Calvinists, we should realize as we contend with other Christians that we might be wrong.
I have always liked this analogy. If all Christians were asked to write out the word Christ, we would all cross of T's and dot our I's differently but we would recognized the word Christ. So it is with our theology.