When Peter speaks of adding brotherly kindness as the next habit, he uses the Greek word philadelphia. This of course is the word which means “brotherly love” (and from which the city in Pennsylvania derives its nickname). This habit is a reminder to us that as believers in Christ, we share a spiritual kinship with all other Christ-followers. Jesus commanded his disciples to love one another, a command which is repeatedly emphasized throughout the New Testament. In fact love for other believers is to be a defining characteristic of a follower of Jesus (John 13:35).
Because this love for other believers is commanded, it should be obvious that it is not based on mere feelings. Instead it has to be based on our shared spiritual kinship with God the Father and the knowledge that our fellow believers are also beloved of God. It may be the case that we need to remind ourselves of this important truth when we find our fellow believers to be particularly hard to love. We may also need to be reminded that we can be hard to love as well! As Paul writes in Eph. 4:32 “be kind to one another, tender-hearted, forgiving each other, just as God in Christ also has forgiven you.”
Developing this as a habit requires first and foremost that we spend time with other believers, in what is commonly known as fellowship. In some Christian circles, the word fellowship is often used of social interaction before or after the service. The meaning that I have in mind goes deeper than this; it also involves a spiritual component in which our common interest is in pursuing godliness with other like-minded brothers and sisters. True biblical fellowship spurs us on toward love and good deeds along with those who are themselves seeking God first above all else (Heb. 10:24).
It is also in the context of fellowship that we learn to practice the “one anothers” of the New Testament. There are many examples of these commands, such as Rom. 12:10: “Be devoted to one another in brotherly love; give preference to one another in honor.” Other “one another” commands can be found in Rom. 15:7, Gal. 5:13, Eph. 4:32, Col. 3:12-13, 1Thess. 5:11, and Heb. 3:13. It is only in fellowship with other believers that we can put into practice these essential relational commandments that not only build us up but also build up the Body of Christ together as a whole. A promise which applies to this important habit is found in Eph. 4:15-16: “but speaking the truth in love, we are to grow up in all aspects into Him who is the head, even Christ, from whom the whole body, being fitted and held together by what every joint supplies, according to the proper working of each individual part, causes the growth of the body for the building up of itself in love.”
Sadly, some believers make the mistake of thinking that the Christian life can be lived independently of any connection to a gathering of other believers. But this is not how God has designed it. The Christian life is not meant to be lived in isolation from other believers. In fact it is doubtful that such a life can be called Christian at all in any meaningful sense. We need the other members of the Body of Christ just as they need us (1 Cor. 12:12-25). It is essential therefore to regularly meet with a group of fellow believers for worship, teaching, and fellowship. For most Christians this is best accomplished by becoming a part of an existing local church. Even better is to become a part of a small group of serious-minded believers that meets together not just on Sunday mornings for mutual encouragement.