To review: a sound church is one that is committed 1.) to obeying Scripture as its final authority, 2.) to a steady diet of expositional preaching that explains the meaning of the Bible, and 3.) to understanding Scripture within its proper context of systematic and biblical theology.
The next commitment of a sound church is exceedingly important, because it is the kind of thing that identifies what the church is. The church is made up of those who follow Jesus Christ. But following Jesus is an ambiguous expression. Are we following Jesus if, before making any decision, we ask what Jesus would do? (Side observation: I suspect he wouldn’t wear one of those bracelets, although I may be mistaken.) While the Bible does point to Jesus as an example for right living, the Christian message can never be reduced to exhortations to live like he did. To quote the great Presbyterian J. Gresham Machen, genuine Christianity can be distinguished from spurious Christianity in this way: for some, Jesus is the example of faith, but for the true Christian, Jesus is the object of faith.
There is a world of difference between these two conceptions of Christianity. If Jesus is merely the example of faith, the Christian message is one of works: be saved by doing what Jesus did. The problem with this should be obvious: who among us would dare claim that we live up to this standard? To reduce salvation to following the example of Jesus is to lay a burden on people that no one can meet. A message of works can produce only two kinds of people: the insufferably arrogant who falsely believe they can meet the standard, and the despairing who know they can’t.
By contrast, to say that Jesus is the object of faith is to maintain that it is of high importance that all people affirm certain truths about Jesus. We’ve considered this already in Paul’s explanation of the gospel in the opening of 1 Corinthians 15. The gospel is, quite literally, good news. It is a message to be believed. The core of this belief is that Jesus died for our sins, which means that we need to believe (at least) that we are sinners and that there is something about Jesus that makes his death the means by which I can be delivered from sin.
To believe this gospel is to be converted; this is what it means to be saved. Any church that fails to make this message central to its entire operation has abandoned its real reason for existence. We should not be surprised, then, to find that this message, the necessity of saving faith in Jesus, characterized the apostolic preaching in the book of Acts. In his very first message, Peter explained to his audience who Jesus is, and concluded by instructing them to “repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins.”
To insist on the importance of conversion, then, is another mark of a church with its priorities in order.