One of the earliest American history facts I remember learning is that Philadelphia is the "city of brotherly love". As we studied the history of the constitution and the infant republic, this town was featured prominently. It would be many years before I realized that the name of the city was lifted directly from the pages of Scripture.
Philadelphia, or "brotherly love" is the noun form of one of the three Greek words for love used in the New Testament (the verb form is phileo; the other verbs are agape and storges; a fourth word, eros, is not used in the New Testament.) While agape refers to divine love or to self-sacrificial love, and storges to natural love such as that a mother has for a child, philadelphia refers to love between individuals - specifically, the love that should exist between Christians. Interestingly, the root word, philos, simply means "friend" and was used to refer to "one of the bridegroom's friends who on his behalf asked the hand of the bride and rendered him various services in closing the marriage and celebrating the nuptials". We're talking about a love that involves a level of trust and deep relationship.
In his classic The Four Loves, C. S. Lewis explores each of these words. He writes of philos: “Friendship arises out of mere companionship when two or more of the companions discover that they have in common some insight or interest or even taste which the others do not share and which, till that moment, each believed to be his own unique treasure or burden” (Strong's Concordance). In other words, the Holy Spirit inspired Paul to choose not the self-sacrificing agape love, or the natural storge love, but the relational philos love to define the love that God taught these believers to have for each other.
Love for one another is so important to the heart of God that when the founders of this fledgling church were torn away from them, God stepped in to teach love directly to the church. Certainly phileo love is tied to agape love; the word in the second part of verse 9 is agape. God taught them to love one another with His divine, self-sacrificing love - but it played out in ways that reflected the unique philos love. Why is that? I believe it's simply this: Believers always have Jesus in common.
When we encounter another follower of Christ, we have found something in common, as Lewis described. In a place like Thessalonica, where believers were in the minority and faced persecution, realizing that they had relationships based on the common bond of Christ was crucially important to the young church. Those social bonds would strengthen faith and help them grow to maturity. Furthermore, in the first century there were no denominations or multiple churches within a city. There was no place to go if you couldn't get along. True "brotherly love" was essential for the church to rise above the differences as God brought people from all walks of life - Jew and Gentile, slave and free, male and female - into the church to make them all equal before Christ. And that's a beautiful thing.
I've certainly experienced some of the beautiful diversity of the philadelphia love within the body of Christ. I think of one friend who is as different from me as I can imagine. I'm a southern girl; she doesn't quite get us. I don't have an artistic bone in my body; she is creative in every way imaginable. I dislike pink and girly frou-frous; she enjoys what is often called "the feminine touches". Yet because of Christ, I met her and gradually developed a relationship of mutual love and appreciation for our differences. She has been incredibly encouraging about my teaching; prays faithfully for my ministry requests; and demonstrates in every way that we have true phileo love for each other. I hope you can think of your own example.
We were created for relationship - with God and with others. Not everyone has a spouse; not everyone has children; but we all have the opportunity to have friends. We can enjoy things we have in common with our friends from all walks of life, but there is a special friendship among believers who have Jesus in common. Paul urges us, through the inspiration of the Holy Spirit, to pursue this love, "more and more".