I'm not at all sure how a person can believe a thing is true and at the same time believe that people who disagree on that issue can be correct also. This is the law of non-contradiction: Two contradictory propositions cannot be true in the same sense at the same time. This is a standard rule of logic. It's true that there are those people who claim to reject the law of non-contradiction. But they cannot reject it without affirming it. If the law of non-contradiction was invalid, then there would be no difference between saying "I accept the law of non-contradiction" and "I reject the law of non-contradiction."
Unfortunately, it seems this kind of thinking has crept into Christianity as well. You see, there are certain issues within Christianity about which people have disagreements. Disagreements over doctrine, some essential, some peripheral. Heck, there's even disagreement about what doctrines are essential or peripheral. In the face of these unfortunate conflicts, some Christians, in what may be a noble attempt to smooth things out, have adopted a mantra that says "doctrine divides" and they seek to avoid conflict by avoiding these sorts of controversies, perhaps never taking sides themselves, trying to stay above the fray.
It might be useful at this point to understand what the word "doctrine" means. Doctrine is quite a broad term, actually, it means little more than a body of knowledge that is taught and understood. That's pretty much it. If I teach that 5+5=10, that is doctrine. If I teach that the Earth is round, that is doctrine. For that matter, if I teach that the Earth is flat, that too, is doctrine. It's false doctrine, but because it is something I'm teaching, we can still call it "doctrine." Note that just because we refer to a body of knowledge as "doctrine" doesn't mean that body of knowledge is true. If someone teaches that Jesus Christ is one of many ways to get to Heaven, that is doctrine just as mush as if someone teaches that Jesus Christ is the only way to eternal life. One of those is false and one of those is true. But both are examples of "doctrine."
So the question is, "Does doctrine divide?" And the answer is a resounding "Yes!" But there's another question that comes along with that: "Is that a good thing?" And again, the answer is a resounding "Yes!"
Now, see, some folks are squirming in their seat after reading that. This is uncomfortable. But notice something about this "doctrine divides" mantra: it is doctrine; that which is taught. So right away, and though they may not realize it, the person who is trying to unite Christians by ignoring doctrine is actually using doctrine to divide. Of course, it's not possible to use doctrine to insulate people from doctrine and/or doctrinal disagreements. It's self-refuting.
Why is division over doctrine a good thing? The entire Bible is built on the idea that truth needs to be divided from falsehood. That is why the Bible was necessary. Doctrinal differences is what separates Christians from, say, Jehovah's Witnesses or Mormons. It's what separates Christians from Catholicism. It's what separates Christianity from Islam and every other world religion. Doctrine is important. It is worth discussing, debating, and otherwise making a heartfelt effort to come to a conclusion about. Now granted, some doctrines are more important than others. And I'll also grant that differences in doctrinal understandings should not result in people being hostile to each other. But the Bible is there to provide answers. It's not just a cute story that can be interpreted any way we like.
Is there support for the idea that doctrine (what which is taught) is emphasized in the Bible? Of course. Consider the following verses:
Mark 1:22 And they were astonished at his doctrine: for he taught them as one that had authority, and not as the scribes.
Whose doctrine? Jesus' doctrine. Jesus taught, and what He taught was doctrine. And the Jewish leaders were astonished at the content of His teaching. Jesus didn't avoid teaching what apparently were controversial doctrines (the Jews didn't like what He taught!!) under this "doctrine divides" template, did He? No. He taught, and what He taught was important.
John 7:16 Jesus answered them, and said, My doctrine is not mine, but his that sent me.
Did Jesus think doctrine was important? Yes! Did He avoid teaching doctrine for the sake of unity? No!!
John 7:17 If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.
Here we get into discerning between good doctrine and bad doctrine. Doctrine that is "of God" or doctrine that just represents man's own opinion. There seems to be some emphasis here on making discernments between false doctrine and true doctrine.
Acts 2:42 And they continued stedfastly in the apostles’ doctrine and fellowship, and in breaking of bread, and in prayers.
Once again, the apostles were not avoiding teaching doctrine for the sake of unity.
Rom. 16:17 Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them.
Here Paul is telling us again to be discerning; to learn to spot doctrine which is contrary to the doctrines he and the apostles had taught, and to point out those who are creating divisions with these false doctrines!
Eph. 4:14 That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive;
Hmmmm. Another passage emphasizing discernment. Don't be naive like children, believing every doctrine that comes along. Men lie in wait to deceive with false doctrines, so be discerning. Yes, doctrine divides, alright.
1Tim. 1:10 For whoremongers, for them that defile themselves with mankind, for menstealers, for liars, for perjured persons, and if there be any other thing that is contrary to sound doctrine;
Contrary to sound doctrine? Another allusion to the distinction between doctrine that is sound and doctrine that is unsound. Division. Discernment.
1Tim. 4:6 If thou put the brethren in remembrance of these things, thou shalt be a good minister of Jesus Christ, nourished up in the words of faith and of good doctrine, whereunto thou hast attained.
Once again. Good doctrine. Not bad doctrine. There's a difference, a division, between the two.
1Tim. 4:13 Till I come, give attendance to reading, to exhortation, to doctrine.
Study doctrine!! Know it!! Don't avoid it!!
2Tim. 3:16 All scripture is God-breathed, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness.
Doctrine is profitable. That merely means it serves you well. It is valuable, it is important. And all scripture contains doctrine.
2Tim. 4:2 Preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine.
Teach doctrine, Paul says to Timothy.
2Tim. 4:3 For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears
Interesting… Paul is warning Timothy that at some point people will flee doctrine. They will abhor it. They will not endure it!! And Paul is saying this is bad!! Doctrine divides!!
Titus 1:9 Holding fast the faithful word as he hath been taught, that he may be able by sound doctrine both to exhort and to convince the gainsayers.
Sound doctrine (good doctrine) enables you to exhort and persuade those who would teach incorrect doctrines!!
2John 1:10 If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed
Another verse insisting that we be discerning! John tells his audience not to let a man into your house if he teaches another doctrine! If we don't know what good doctrine is, then how will we know when someone's bringing bad doctrine? How could we follow John's advice here if discerning between good and bad doctrine were not imperative? Yes, doctrine divides. John says it should divide.
I think it's clear by these passages that there is much emphasis in the Bible on correct doctrine. Doctrine is essential. It's unfortunate that there are differences out there. That certainly makes it more difficult. But as I've encountered this controversy or that controversy, I've found that the controversies tend to drive you deeper into the text--particularly if you understand the importance of discerning doctrine and having the correct understanding--and as I've dug into the issues and sought the truth, being willing to re-examine the doctrines I've been taught my whole life, I have found answers. I have found resolution. And while I have had to abandon my previous understandings of certain issues, on other issues I have found my understanding to be correct. In both cases, my understanding is increased and my faith is reinforced.