Christianity as a Relationship
In order to understand the nature of discipleship it is also important to recognize that Christianity is about a relationship. Many are familiar with the notion that in becoming a Christian one becomes a child of God. We receive God, our Father, who cares for and attends to His children—even more than a loving earthly father. All of this is certainly true.
There is a danger here, as I see it. Many Christians think of having a relationship with God in terms of their own personal gain! God is there for me when I need Him. The focus of which is on God being there for me. Certainly, there is a personal gain, and certainly God is there for us. But if that is what it is about, then it is not predicated on love, but on selfishness. This means that we have the roles reversed. Instead of surrending to Christ as Lord, Christianity becomes about me. This leaves myself as Lord.
So, it is indeed about a relationship. But that relationship begins and ends with Christ as Lord.
Discipleship as Imitation
The fundamental feature of Christian discipleship, then, is that it is about becoming like Jesus! Paul says, “Be imitators of me, just as I also am of Christ” (1 Cor 11:1). In Ephesians, Paul says, “Be imitators of God” (Eph 5:1). Since Paul was convinced that he was striving to imitate Christ in his own life, he felt that he could urge his disciples “be imitators of me” (1 Cor 4:16). What an incredible statement! Instead of saying “imitate Jesus”, Paul says “imitate me.” Now, I do not think that we can suppose that Paul was arrogant here. I suspect that Paul meant, and his readers knew, that he was doing his best to follow Jesus and was asking them to follow along!
That the goal of the Christian life is to attain Christlikeness is why Paul says, “We proclaim Him, admonishing every man and teaching every man with all wisdom, so that we may present every man complete in Christ. For this purpose also I labor, striving according to His power, which mightily works within me” (Col 1:28-29). Paul says that he labors and strives to present everyone “complete” in Christ. The word for “complete” (teleios) has the sense of attaining the goal, or the end.
Now, we recognize that will not attain Christlikeness in this lifetime. We will, however, in the resurrection: “We know that when He appears, we will be like Him” (1 John 3:2). This is why Paul says,
“that I may know Him and the power of His resurrection and the fellowship of His sufferings, being conformed to His death; in order that I may attain to the resurrection from the dead. Not that I have already obtained it or have already become perfect, but I press on so that I may lay hold of that for which also I was laid hold of by Christ Jesus. Brethren, I do not regard myself as having laid hold of it yet; but one thing I do: forgetting what lies behind and reaching forward to what lies ahead, I press on toward the goal for the prize of the upward call of God in Christ Jesus” (Phil 3:10-14).
Imitation in suffering
Imitation of Christ includes suffering as Jesus suffered! Suffering is a fundamental component of being a Christian. Peter notes that Jesus suffered as an example for us: “For you have been called for this purpose, since Christ also suffered for you, leaving you an example for you to follow in His steps” (1 Pet 2:21). This is why Paul says that our imitation of Christ includes following Him in the way of suffering: “You also became imitators of us and of the Lord, having received the word in much tribulation with the joy of the Holy Spirit” (1 Thess 1:6). Later, in the same letter, Paul notes, “For you, brethren, became imitators of the churches of God in Christ Jesus that are in Judea, for you also endured the same sufferings” (1 Thess 2:14).
This is why Jesus states that “if anyone wishes to come after Me, he must deny himself, and take up his cross and follow Me. For whoever wishes to save his life will lose it, but whoever loses his life for My sake and the gospel's will save it” (Mark 8:34-35).
 Cf Luke 11:13 “If you then, being evil, know how to give good gifts to your children, how much more will your heavenly Father give the Holy Spirit to those who ask Him?”
 The different translations help us to see the full meaning of the word: ESV, NET, NIV, and NRS render it “mature in Christ”; and the NLT uses a phrase “perfect in their relationship to Christ.”