So, let's quit treating people who disagree with us as heretics.
3 churches I attended in the 70's would bar me from membership today because my beliefs have changed. I was saved in '72, and am still saved in '05, so that's not the issue. The issue is doctrine. '72 Kevin would be allowed to fellowship at XXXXXX Bible Church, but '05 Kevin would not. This amuses me! And it disappoints.
(What does this do to Calvin's belief that the catholicity of the church spans time as much as space?)
I contend that doctrine is secondary. Most people will testify to this to some degree, but in the end they join a denomination, making doctrine primary in their practice.
Doctrine is not an end, but a means (and sometimes it is just plain mean.) The end is knowing Jesus Christ, and we know Him by living with Him. That's why no one can "test out" of life. You can't prove you have all the doctrines right, and go straight to heaven. Life is hard, much harder than straightening out some twisty doctrines.
Doctrine's proper application is helping us to navigate this fallen world.
Disaster strikes, and we become confused. Did God predestine this disaster? Does He care about it? Bring out the doctrines! They can really help us understand life, and react to it wisely. A wise brother can use a correct doctrine of predestination to be a tremendous comfort. He can straighten the path for that confused saint.
Assume, though, our wise brother was not available, and our confused saint did not have a solid understanding of predestination. Is it time to excommunicate him? Is it time to brow-beat him about his muddled thinking, the drivel he calls doctrine, and wolves that must be driven from the fold?
There is a time for rejecting a heretic. The time is when the man cannot release foolish questions and needs to strive. That man is still in his sin.
Titus 3:9-11 But avoid foolish questions, and genealogies, and contentions, and strivings about the law; for they are unprofitable and vain. A man that is an heretick after the first and second admonition reject; Knowing that he that is such is subverted, and sinneth, being condemned of himself.
Gal 6:1 is much more commonly useful, though: Brethren, if a man be overtaken in a fault, ye which are spiritual, restore such an one in the spirit of meekness; considering thyself, lest thou also be tempted.
We need to quit running each other off when we disagree, even about the big things of doctrine. Denominating is sin. Wrong doctrine is just wrong doctrine.