But there is a world of difference between tolerating an error and tolerating a person who is in error. It is impossible, when I really think about it, to tolerate an error other than my own. An error (in this context) is a mistaken understanding held by a person. I have no more ability to tolerate another person's erroneous idea than I have to correct it myself. The error is his own to either tolerate or correct, and I can better help him correct it if I treat him as a brother.
So the question really comes down to whether I should tolerate the person who holds an erroneous idea, not whether I should tolerate the error. I have learned that I can completely reject what I believe to be another person's erroneous thinking and still love him as a brother in the Lord. Jesus died for him as well as for me, even if we are both mistaken on some things, as we both most certainly are. If his error is a fatal one, or a destructive one, or if I think it is, I certainly should endeavor to persuade him of that out of love. But treating him as a brother does not make his error mine.
Of course, there are situations where we are not even to tolerate the erroneous person. When someone insists on continuing in immorality, or tries to divide believers into factions, he is to be rejected from our Christian associations. If someone teaches that Jesus Christ was not God in the flesh, or denies the resurrection, or other aspects of the good news, we are to avoid him. These are the scriptural reasons to be intolerant of an erroneous brother, because in other matters, we humans may all have some erroneous thinking yet to be purged from our minds.
God Almighty created all of our intellects differently. Some are born with an extensive one, others (like me, perhaps) were born with limited intellects. (They say intellect has a lot to do with memory, and you can ask my wife, my memory is "like a vapor!")
The great thing about being in Christ is that we are all, from the least to the greatest in wealth, maturity, and intellect, gathered around the same table. I, for one, don't want to be the one to push someone away from that table. He is Jesus' guest, not mine.
- Romans 15:7 - Accept one another, then, just as Christ accepted you, in order to bring praise to God. (NKJV)
So with few exceptions, I must be longsuffering with my brother in spite of his own personal errors, secure in the knowledge that he is called to be longsuffering with me in spite of mine.
- Ephesians 4:1-3 - I, therefore, the prisoner of the Lord, beseech you to walk worthy of the calling with which you were called, with all lowliness and gentleness, with longsuffering, bearing with one another in love, endeavoring to keep the unity of the Spirit in the bond of peace. (NKJV)