I have always thought of the "purpose statement," which became so popular in the churches during the last few decades, much like the various other stilts and fads of evangelicalism--beggarly. Nevertheless, like most things, focus on this particular device has had its practical effects; it helps to draw the worshiping community into a single-minded direction. Fanny and I certainly experienced several positive corollaries in our youth ministry as a result of self-consciously encapsulating our community's purpose. It went something like this...
We Assemble in the fellowship of the Spirit to thereby Grow in the knowledge and grace of our Lord Jesus Christ and Adore the living God with heart, soul, mind, and strength, for the Proclamation of the gospel in word and deed, and for the Evangelization of God’s world.
Assembling together (fellowship)
Growing in knowledge and grace (discipleship)
Adoration of God (worship)
Proclaiming the gospel in word and deed (ministry)
Evangelizing the world (missions)
Above is the formulation of both the purpose statement and core values that controlled the youth ministry philosophy that my wife and I, with our youth leadership, developed for our group about eight years ago. Regarding its relative, practical effectiveness, we found it to serve well in growing our community in depth and breadth.
You may recognize that the core values are merely extrapolated bits of the purpose statement. For me, the distinction between the core values (CV) and the purpose is only one of emphasis. The purpose statement (PS) offers a unified, coherent framework, which communicates the CV in terms of their general relations. The PS is simply a singular expression of the community’s several CV. Secondly, just as the PS is undergirded and controlled by the CV, the CV are organized and controlled around the biblical summum bonum, agapē, love, which also serves as a mnemonic device for ease of memorization.
First, then, is the ground motive of the ministry, agapē, love. Of the triadic “core values” of Christianity—faith, hope, and love—love is central (1 Cor. 13:13). It is therefore at the center of every vivacious ministry. We are to do all things in love (1 Cor. 16:14). Our ministry should be controlled by the love of Christ (2 Cor. 5:14). In a healthy ministry, love for one another will abound and increase (1 Thess. 3:12). And since love is the primary action in the Great Commands, the failing at this point in ministry must then be the greatest of sins (Mk. 12:30—31). Therefore, love is to be the crux of the ministry’s philosophy and praxis.
Secondly, the AGAPE makes the mnemonic device that introduces each of the ministry’s CV. This listing of CV does not represent any hierarchy of priority or importance; rather, as expressed by the PS, they are an indissoluble set, which are isolated only as a matter of emphasis. The first listed of these is Assembling together. This is meant to highlight several things. This is at once fellowshipping and being the Church. “Assembling” happens to be the first definitional entry for ekklēsia (“church”) in most Greek lexicons. This is meant to stress that youth ministry is not a part of the church; it is the church. We are an integral page in God’s redemptive-historical plan, which Christ himself is actualizing (see, e.g., Matt. 16:18). Further, this assembling is in the “fellowship of the Holy Spirit” (2 Cor. 13:14). As the grace of Christ and the love of God works out the global temple-building plan through the gospel, the Holy Spirit is personally present with the “Assembly,” corporately (2 Cor. 3:16; 6:16ff) and individually (1 Cor. 6:19ff). Therefore, there is a weighty joy in being a youth ministry.
The second listed CV is Growing in knowledge and grace. This is what I believe is a biblical turn of phrase meaning discipleship (2 Pet. 3:18; cf. 1:2; Matt. 28:19). Granting that we live in what is likely one of the most biblically illiterate epochs of church history, I do not think that this CV can receive too much attention. Notice that it is both knowledge and grace. Today there is so much emphasis on felt-needs and competition with the entertainment offered by the culture, not to mention the ubiquitous (and culpable) disparaging of “dusty, old impractical theology” at all levels within the church (and sometimes even in the academy!!), that it is little wonder that our young people haven’t a clue how to respond to the manifold so-called intellectual attacks they encounter in the university and in life! Students must learn the content of the redemptive story in which Christ is the consummative center, and be nurtured in a full-orbed biblical worldview, if the God-glorifying, Christ-honoring, world-changing lives we hope to be a part in developing come into their own. Grace is simply the God-given, pastorally-guided application of these things.
The third point of the CV is Adoring the triune Majesty. If worship is not the unifying weld that binds a ministry together, that ministry has lost its meaning. The redeemed community has one common thread, they all are those who have “turned from idols to worship and serve the living and true God” (1 Thess. 1:9). Personally, I believe that youth ministries today jumps between one horn or the other of the worship style dilemma. When “worship” is little more than a parody of the students’ favorite rock/pop band concert, it is gored by the horn of worldliness. If, on the other horn, we expect students to connect in one accord and one heart with God and one another in worship, grandma’s Gospel choruses will likely impale the heart. I believe that traditional forms of worship must shape the service, while allowing for manifold expressions. Contemporary hymnody—modern folk’ish music with theologically rich verse—is moving toward a third way off the dilemma (e.g., The Gettys, Indelible Grace). This generation’s taste in music is so trans-genre, appealing to the popular top 40 style of instrumentality is not necessary to provide an ambiance that nurtures the heart of the students’ worship. Worship in whatever expression (e.g., music, art, liturgy, exposition, etc.) must have a sense of otherness; it needs to be different from the world, not more like it.
Proclaiming the gospel in word and deed is the fourth CV in the list above. The preaching/teaching/hortatory/counseling aspect of youth ministry will be either moralistic or gospel-centered. It cannot be both. The gospel is not something we merely lay hold of as a starter, something that just comes before we move on to more complex and practical matters. Rather, the gospel must be the basis of all that the ministry is and does. For example, when Paul wishes to unpack the “mystery of godliness” for his young student, Timothy, what does he say? “Great indeed, we confess, is the mystery of godliness: He was manifested in the flesh, vindicated by the Spirit, seen by angels, proclaimed among the nations, believed on in the world, taken up in glory” (1 Tim. 3:16 ESV). What, then, does Paul prescribe for training in godliness? The kerygma, the gospel! But the gospel is not only something proclaimed in word; it is also proclaimed in deed. The students should understand that the sacrament of the Lord’s Table is also a proclamation of the gospel (1 Cor. 11:26), for instance, as are so many other good works of love and mercy, especially one to another (1 Jn. 3:16—18).
The last entry under CV is the Evangelization of God’s world. One facet of our ministry back home (in Kansas, that is) was what I called the Great I.A.M. Project. The acronym I.A.M signifies Immediate Area Missionaries (but, of course, the verbal form of God’s covenant Name is the ultimate grounds rooting the acronym; see Ex. 3:4; cf. Jn. 8:58, etc.). Mission is not something we do as much as it is a journey we are on. This is certainly the sense of the flagship passage for modern missions, Matt. 28:18ff, the Great Commision. The first word of Matt. 28:19, “Go ye therefore…” (poreuomai), literally means traverse, travel, or journey. Moreover, it is passive, meaning it is something we are on rather than an action we are to do. For those truly following Christ, they are “Going…therefore…” by virtue of their following him. And as we “traverse” this pilgrim’s land, we are commanded to make disciples, since the lives of our fellows are the only baggage that will make it with us to our Destination. Thankfully, because of who the Captain of our salvation is, we needn’t worry about lost baggage (Heb. 2:10; Jn. 6:44)!
 I would briefly mention that I do not share the popular and sharp distinction between agapē and phileō love. It is often said that agapē is the divine-sort of love, whereas phileō is a more general brotherly-sort of love. Both terms, however, have significant semantic overlap. For example, Paul writes of Demas’ “love” for the world, having thus abandoned Paul (2 Tim. 4:10). Moreover, in the LXX we read that Absalom “loved” Tamar, his half-sister, and showed his “love” by raping her (2 Sam. 13:1f). In both of these cases, a verb form of agapē is used for “love.” Contrariwise, in Jn. 5:20, Jesus declares the Father’s “love” for the Son. Here, in this expression of the divine, intra-Trinitarian love, the verb form of phileō is used. Therefore, I am not convinced that the emphasis on the Greek words is as significant as many make it to be. Nevertheless, agapē being the most common term for expressing our love for God, fellow believers, and our neighbors, we thought it best.
 Notice that in 2 Pet. 3:18, the verb “grow” is in the present, active imperative (i.e., a command), meaning, “but keep on growing in the knowledge…etc.” The imperative is also present in Jesus’ command to “make disciples…” (Matt. 28:19). Youth ministry is therefore bound by the authority of Christ speaking in the scriptures to disciple its flock. This command is a core value, not so much because of the value of the action’s effects, but the infinite value of the One from whom the command issues.
 I say for modern missions here because one cannot find an evangelistic-missional application of the Great Commission in the writings of the Apostolic Fathers or the Patristics. In nearly every case, this passage is cited in defense of the deity of Christ or orthodox Trinitarianism.