Division, disunity, and discord are constants in a world ruined by sin. On virtually every front, over every conceivable issue, mankind is at war with itself. Driven by pride and greed, everyone wants his or her own way, and no one is given to sacrificing or surrendering for the sake of another.

And even when the people of the world do manage to work together—whether in a common cause, a business venture, or a marriage—you can be sure that self-interest undergirds their cooperation. That’s what it means to be “dead in your trespasses and sins” (Ephesians 2:1)—apart from Christ, we lack the ability to do anything truly selfless, righteous, or good.

Thankfully, while the church is filled with sinners who share the same selfish instincts, God has freed His people from the bondage of their flesh and given them the ability to work together, sacrificing themselves for the sake of His kingdom and each other.

That unity among believers is a powerful encouragement. It buoys our spirits in the midst of trials, energizes our spiritual growth, shoulders our burdens, promotes accountability to live holy lives, and emboldens us to proclaim the truth of God’s Word. Christians are right to celebrate the unity the Lord has forged between us, and must protect it against Satan’s assaults.

But we need to keep that unity in proper perspective, along with its implications. We love the imagery of standing together with other Christians, but are we giving too little thought about what we’re standing against?

We recently brought that question to John MacArthur. Here’s what he said:

Many believers today are quick to assert their solidarity in the gospel. But what are the implications of that unity? It’s not enough just to affirm that we stand together for the gospel—we also need to understand what we’re united together against.

In the coming days, we’re going to consider some of those implications, and some specific issues and movements that our unity in the gospel demands we oppose.