“Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin. For we have come to share in Christ, if indeed we hold our original confidence firm to the end” (Hebrews 3:12-14).
We have a desperate daily need for one another. This is true for couples as well as single people. Over time, married people settle into habits and patterns of life that cater to our worldly appetites. And instead of spouses confronting one another, we conspire together to build our own personal kingdoms rather than God's. We choose together to deny the power of the Gospel by following the course of this world rather than renewing our minds. We clearly see this in the Bible in couples like Ahab and Jezebel and Ananias and Sapphira.
On the other hand, when a couple conspires together for the glory of God, a powerful force for the Gospel can be established. We clearly see this in the Bible in a couple like Aquila and Priscilla. However, behind every Aquila and Priscilla we'll likely find someone like the apostle Paul, encouraging and challenging and stirring up to love and good works. Deitrich Bonhoeffer says it this way:
When Christians live together, at some time and in some way it must come to the point that one Christian personally declares God's Word and will to another. . . . We talk to one another about the help we both need. We admonish one another to go the way Christ bids us to go. We warn one another against the disobedience that is our undoing. We are gentle and we are firm with one another, for we know both God's kindness and God's firmness. . . . When another Christian falls into obvious sin, an admonition is imperative, because God's Word demands it. The practice of discipline in the community of faith begins with friends who are close to one another. Words of admonition and reproach must be risked when a lapse from God's Word in doctrine or life endangers a community that lives together, and with it the whole community of faith. Nothing can be more cruel than that leniency which abandons others to their sin. Nothing can be more compassionate than that severe reprimand which calls another Christian in one's community back from the path of sin. When we allow nothing but God's Word to stand between us, judging and helping, it is a service of mercy, an ultimate offer of genuine community.