Actually, can we escape their interconnectedness? Matthew 28:18-20 seems to entwine them. 1. Explain the gospel to strangers 2. Demonstrate to followers how to OBEY (DO) the things I have shown to you.
Jon Speed has observed that in our Lord’s ministry, His evangelism efforts were aimed at strangers 86.5% of the time (and many of the encounters that could be characterized as among friends began with a stranger encounter). In the book of Acts, 83% of evangelism interactions was with strangers. Throughout the NT, friendship evangelism occurred, but the preponderance of evangelistic effort was among strangers.
In contrast to evangelism, discipleship in the bible reflects an almost exclusive use of the friendship approach. Paul could say to Timothy, “…thou hast fully known my doctrine, manner of life, purpose, faith, longsuffering, charity, patience, persecutions, afflictions, which came unto me at Antioch, at Iconium, at Lystra; what persecutions I endured: but out of them all the Lord delivered me…” 2 Tim 3:9-11 One of the key roles for those more mature, and their key means of doing do, is to teach by being examples rather than by lecture (see Phil 3:17; I Thess 1:7; II Thess 3:9; I Tim 4:12; I Pet 5:3; etc)—examples that we should follow/emulate/pick up and do ourselves!
So, “being on mission” as His followers revolves around two areas of labor: stranger evangelism and friendship sanctification. i.e., followers of Christ who become “fishers of men.” Perhaps this opens up another layer in understanding our Lord’s statement in Matt 18:20, “For where two or three are gathered together in my name, there am I in the midst of them.” It isn’t in the large Sunday morning crowd, but in the two’s and three’s spending time together through the week, where both evangelism with strangers and discipleship among friends takes place.
It does not take great effort to become able to explain the gospel adequately. But to manifest Christ evidentially through our lives—and to take the time to be closely involved in the lives of others—takes the cross work of dying and the power to become sons of God living. I suppose it is the sacrificial worship 0f Romans 12 manifesting the life of Christ through us (II Cor 2:14, 3:3, 4:2, 4:10-11, 11:6).