Life together in Christ is quite an adventure, and this sometimes comes as a shock and surprise. It is easy for us to think that if we love Jesus, then loving our neighbor should be easy. And if we think that, how much easier will it be for us to love our brothers and sisters? Right? Not exactly.
The problem with the closeness of covenant communion is that it means that all of us have moved closer together—which means that everyone is now in range. If we sin, when we sin, we do so with others close by. This means it is easy to get hurt, and doubly easy to want to retaliate. Because this is the set-up, this is precisely why the apostles are constantly warning their congregations against the bitterness of in-fighting.
For just one example, what did Paul tell the Galatians? He said that we were to serve one another in love (Gal. 5:13). Sounds harmonious, right? Sounds lovely. But what does he add in the next breath? “But if ye bite and devour one another, take heed that ye be not consumed one of another” (Gal. 5:15). Bitterness wants to bite, and bitterness does this because bitterness wants blood. It might be psychic blood, or emotional blood, or actual blood, but bitterness always ends with the biting and devouring.
There is an irony here. Bitterness demands blood, but at the same time, bitterness hates God’s solution to this devouring impulse—and that solution is blood. The blood of Jesus is the only reality that can stop the insatiable desire that bitterness entails. This is a craving that only the cross can deal with. This is why men invent theologies that empty the cross of this power. They do not want a substitutionary death of Christ, under the wrath of God, because that is the shed blood that causes the demonic desire to devour to flee.