Today's church often accepts whatever their leaders tell them is solid doctrine. When somebody says "that preacher is really solid", what they typically are saying is that this teacher agrees with them on certain tenets of systematic theology. But is that what Scripture calls good teaching, or is it just what we call "solid"? In other words, what makes something actually "solid"?
When we have the discussion about whether someone is a solid teacher or a heretic, we have to look at what Scripture calls false teaching. Does God's Word say, "Anyone who doesn't teach sovereign election is a false teacher"? Does it say, "Whoever doesn't believe that salvation is by grace alone through faith alone is a heretic"?
And what happens when we do say those things? Usually two people or groups of people decide that they are going to stick to what they know is "solid" teaching, and if the other party won't agree with them, then they resolve to not be part of the same church body or under the same eldership and teaching. But is this Biblical?
I can hear it now - a person saying, "But we can't compromise truth for unity." Yes, this is true. Truth can never be compromised for unity. At the same time, unity can never be compromised for truths that are not essentials to saving faith. And, to be honest, the majority of truths in the Scriptures are not essentials to saving faith. They are true things about saving faith, but they do not determine whether a person is saved and secured by the Holy Spirit; therefore, these truths, while true, do not determine a person's right to be treated as an equal brother or sister in Christ.
So the question becomes, "Where do we overlook differences, and where do we remain unbending?" We have to look at a few things to answer this question. First, we have to look at how Jesus himself shared the Gospel. What was his message? Consistently, his message was one of restoration. That's why he always healed people. The promise given to Adam in Genesis 3 was one of restoration - that God would restore the creation. The healing of physical ailments was Christ's demonstration of his ability and power to restore the souls of men to their Creator.
Second, we have to ask which tenets of our systematic theology affect saving faith. Does believing in the doctrine of sovereign election enact or negate saving faith? No. Does believing in a pre-millennial, dispensational theology determine whether a person is genuinely restored by God's saving power? No. Does a statement that salvation by grace is not the main point of the Gospel make someone a heretic? No. Therefore, none of these things should prevent us as a church from seeking unity.
The problem with adhering so tightly to our doctrines at the expense of unity is that it encourages arrogance, gnosticism, and division. Division is strongly condemned in the New Testament. Unity within the body of Christ is probably the most discussed topic in the New Testament besides the Gospel itself. The Gospel is simply that Christ lived sinlessly and perfectly, died, canceled our debt of sin by nailing it to the cross, and rose again, restoring those whom he has saved. That's the Gospel. The rest of the New Testament just discusses how to live in a Christlike way - always with the goal of unity at the forefront.
What's the purpose of unity? It's so that we, as the united and faithful body of Christ, can collectively work together in unison to call people to repentance. How can we do that if we are arrogantly bickering about variations in our systematic theology? Everyone has their camp where they believe that those in other camps are heretics or false teachers or lesser Christians because they don't adhere to "solid doctrine", a.k.a. their version of systematic theology.
When we act in such a divisive way, how are we any better than Muslims? They claim to have the only truth and to be the only true people of God. While we know that's not true (based on their rejection of Messiah as Lord), how are we any different when we say those same things about our Arminian brothers and sisters? Just because we believe one thing is true doesn't give us the right to throw stones at others or refuse to unite with them in purpose and mission.
I am not saying we should compromise truth and accuracy. I am not saying that it's okay to wander around not knowing what we believe and bordering on agnosticism. What I am saying is this: we keep pursuing an accurate and honest interpretation of Scripture based on the historical and grammatical context of Scripture; and we also humbly admit that we don't know everything, we could be wrong, we see where opposing arguments have their merit, and we unite with those who hold opposing views as brothers and sisters who are equally covered by the blood of Christ.
God does not show favorites. Why in the world would we think it's okay for us to do that? "I am of Piper" or "I am of MacArthur" sound an awful lot like "I am of Paul" or "I am of Apollos". This is not okay. Modern evangelicalism and its tendency to divide and follow various people and refuse to pursue unity is extremely unbiblical. It destroys other believers. And it damages God's church.