In my opinion, fundamentalism was nothing other than an interdenominational movement in reaction to institutional liberalism. The definition in Webster's unabridged backs my understanding, when it reads: "a movement in American Protestantism that arose in the early part of the 20th century in reactin to modernism and that stresses the infallibility of the Bible. . . " Bible believing and practicing churches also rejected liberalism, whether fundamentalist or not, so would have been at least sympathetic with fundamentalism. These same churches also agreed with what have been called "the five fundamentals of the faith." These churches, though, never ever took the five fundamentals solely as their standard for separation or unity. They also rejected infant sprinkling and a host of other doctrines held by the fundamentalist movement.
Men are responsible to allign with everything God said in His Word (John 14:15-22). Agreeing to follow everything the Lord said fits into a proper view of repentance (Romans 10:9, 10; Deuteronomy 30:11-14). Making disciples requires "teaching them to observe all things" that Christ commanded. Paul exhorted Timothy that he "mightest charge some that they teach no other doctrine" (1 Timothy 1:3). Paul also wrote in Romans 16:17, "Mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them."
I like the third definition of fundamentalism in Webster's Unabridged: "Strict adherence to any set of basic ideas or principles." I am not a fundamentalist of the movement, but I am a fundamentalist used as an adjective, in fitting with strict adherence to everything the Bible teaches. For that reason, I don't mind someone calling me a fundamentalist. I don't trace any lineage to the beginnings of the fundamentalist movement. If someone transported our church to that period, I wouldn't fellowship with those fundamentalists. I would have sympathized with them like I do with Ian Paisley, for instance, in the matter of perfect preservation of Scripture, but without fellowshipping with him due to his views on infant sprinkling (among other doctrines). I don't take my stand on fundamentals. I take my stand based upon the Word of God. When we stand before Christ, that's all that will matter.