After Israel conquered the land with Joshua leading them, they had a hard time of it to stop fighting.
Two and a half tribes went back home across the Jordan and built an altar at the Jordan. The rest of Israel got hopping mad and sent their army to destroy the two and a half tribes!
Thankfully they listened before they lashed out.
The two and a half tribes had built the altar so they could prove they belonged to Israel in future generations, not so they could worship another god. Israel gives a collective, "Oh, okay," and goes home with a sigh of relief.
Notice Israel had godly intentions in their zeal to fight even their own people. If the altar was for another god, Israel would have been right to fight (see Deuteronomy 13:6-18). But even with godly intentions and a willingness to stand courageous for the truth against any who oppose it, we must be willing to lay down our swords and live at peace with those who do things a little differently but aren't abandoning the one true God.
For a detailed consideration of this in contemporary presbyterianism, I commend John Frame's article "Machen's Warrior Children," found here.
We need to pursue purity and peace among God's people, but those aren't two separate options. If you aren't pure you don't have peace. If you have contention you aren't pure. There are times to disturb a counterfeit peace to root out impurity (Jeremiah 6:13-14). There are times to disturb a counterfeit purity (conformity around minor or surface issues), so you can have truer and deeper peace, even if it's harder. Too often the church thinks pursuing purity is always right, while pursuing peace means compromise. But often pursuing purity overmuch is schismatic, while pursuing peace at the right time brings purity along with it.
So Israel goes home saying, "Maybe we wouldn't have built an altar to make their point, but we see their motive is good, and so we bless them with peace." Let us go and do likewise with our brothers and sisters in Christ.