Some people like to think that separatists love separating to the degree that they are looking to separate. A true separatist looks to unify, but it must be unity, that is, it must unify on and in the truth. Truth is the basis for unity and separation. You try to unify and if it doesn't work, you separate. Noah tried to unify for 120 years and then at a fateful juncture in history, he separated from everyone on earth in the ark. No one else would take the truth, but those eight people. I see myself believing the same idea and the same strategy.
When you are a separatist, you can't wait forever, and you've got to learn when to stop attempting to unify, because you will waste your time. You might call that dusting your feet, as Jesus did. Then you stop sowing pearls before swine. You have to move on.
I have said many times that I'm a separatist, but I don't cut people off. Paul commanded in 1 Thessalonians 5:14, "Be patient toward all men." Again, that's a command. We've got to be patient with people. I recognize that men don't think I'm patient. It's tough to say you're patient. Who can really say that? Men don't think I'm patient, I believe, merely because I do separate. Their idea of patience is never separating.
Some patience waits until the coming of the Lord. You won't be truly vindicated until the end. This is James 5:11, "Behold, we count them happy which endure. Ye have heard of the patience of Job, and have seen the end of the Lord; that the Lord is very pitiful, and of tender mercy." Any genuine believer must keep putting up with unpopularity and rejection his entire life. He must keep enduring the unbelief of the world and the company of a very small minority.
The point of patience of separation is the same point God has with our sanctification. We are waiting for knowledge and maturity, as we can see in 1 John 2 with the little children, young men, and then fathers. You don't jump straight to father, but you go through a process of maturing, which is why 1 Timothy 5:22 says, "Lay hands suddenly on no man." Even Jezebel of Thyatira was given space to repent.
For so many doctrines and practices, I never heard it even preached for a very long period. I didn't even know what I was missing. I was responsible to believe these doctrines and do these practices, but I didn't know about them. I'm still growing. There is still more to learn. I'm not expecting any big doctrinal changes, but I know I understand the Christian life better now and know Jesus more than what I did one year ago.
When someone doesn't believe and practice like you, you don't just cut that person off. You try to persuade that person. You help that person. You go through steps to get him there. Sure, if he shows he doesn't want to listen, you might have to separate.
Separation occurs much faster in your local area. Why? You see those people more. You find out faster whether they are listening. By sheer lack of proximity, you can't find yourself on the same page as some men. This is not an excuse to ignore false doctrine and practice, but you can't get everyone on the same page quickly. Again, you must be patient. The goal is understanding, obedience, true faith, unity, and fellowship. You want that with as many people as possible. In general, this is Romans 12:18, "If it be possible, as much as lieth in you, live peaceably with all men."
What I'm writing here is not an excuse for fellowship with those with whom you should not fellowship. Patience is not ignoring the problem. Along with the concept of patience, you've got that truth in Hebrews 3:13, "But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin." Exhort daily. Don't call what is silence and cowardice, patience. It isn't. You don't just dismiss false doctrine and practice to get together. This is part of patience as well. Before you cooperate and fellowship, you work at unity. You teach, instruct, and correct with patience.
Part of a right understanding of love is 1 Corinthians 13:7: "Beareth all things, believeth all things, hopeth all things, endureth all things." You don't assume someone has a different doctrine than you and just cut him off. At the same time, this doesn't mean you don't ask questions. The example again and again in scripture is 1 Thessalonians 5:21, "Prove all things."
Unity and then fellowship don't come from remaining as oblivious as possible. They come from shining the light. We walk in the light and have fellowship. Fellowship is not keeping everything as dark or grey as possible so no one can either see or knows what is going on. That is just practicing horrible discernment. It's walking into a problem when you know it is there. "A prudent man foreseeth the evil, and hideth himself: but the simple pass on, and are punished" (Proverbs 22:3). You have an obligation not to fellowship with the unfruitful works of darkness, but rather reprove them (Eph 5:11). If you want to be a honorable vessel, meet for God's use, then you must purge yourself from dishonorable vessels (2 Tim 2:21).
Patience is not dismissing doctrine and practice. It is attempting to unify in the full light of day. When Jesus laid out church discipline in Matthew 18, He did it in three steps. I have seen folks turn back at each stage -- after the first confrontation, after the two or three, and then at the time of bringing it to the whole church. Even at the very end of Tribulation on earth, if someone calls on the name of the Lord, the Lord will deliver Him. He saved the thief on the cross.
People who never separate are wrong. They don't really love the people from whom they will not separate. However, a crucial component to the practice of separation is patience.
Be patient when you discipline. Be patient when firing an employee. Be patient with another pastor and another church. Be patient with a missionary you might drop support. Patience goes along with the doctrine and practice of separation.