In any number of settings, a Bible communicator will not be aware of the spiritual/positional status of the listeners. In fact, only the Lord has the capacity to truly understand what is in the heart of man (1 Cor 4:5). Consequently, while we do observe a clear conceptual distinction between preaching and teaching, it may be very helpful in practice for the two to share a close proximity. Peter grounds his exhortations to spiritual progress on reminders of the basic truths of the gospel (2 Pet 1:12, 1:13, 3:1)). Paul recounts the gospel and how the Corinthians received it (1 Cor 15), and moves from that elementary reminder to more complex teaching of the eschatological hope of resurrection. In both of these examples, the writers are addressing believers, so they don’t provide a model for communicating with a positionally mixed audience. Still they show how the gospel can be effectively (and necessarily) interwoven into a didactic situation. In cases like these preaching the gospel becomes an organic part of a teaching moment.
It is worth noting that not a single New Testament book is directly addressed to a mixed audience of unbelievers and believers (Hebrews is understood by some as written to mixed recipients, but this writer suggests the internal evidence supports the epistle’s having been crafted for believers). In fact, John’s Gospel is the only book directly addressing unbelievers (Jn 20:30-31). So, we don’t have a book-level model for addressing mixed audiences.
Within a narrower context we have an important exchange between Jesus and his disciples – some of whom were believing and some of whom were unbelieving (Jn 6:60-66). Jesus used this opportunity to draw a sharp division between believers and unbelievers among his disciples by teaching (6:59) profound truths about Himself (6:53-55), the Father (6:57, 65), and the Spirit (6:63). The result of His teaching was that those who did not believe had no desire to listen to Him any further, and they simply stopped walking with Him from that point further (6:66). This episode is not within the church context, but nonetheless it provides a helpful example of teaching in a mixed-audience scenario. Here, Jesus taught hard truths (6:60) while communicating vividly the condition for eternal life (6:53-58). Some disciples were willing to remain and learn (6:68-69), while others weren’t. In this instance, the priority is teaching – even in a setting in which Jesus knew there were some who were in unbelief (6:64) – and yet He incorporates basic gospel truths, creating a moment of decision for His listeners.
Within the context of believers assembling, there is an obvious priority of teaching over preaching. But the local church is often accompanied by unbelievers – some rather obvious and some not. If we are handling the word well, we will find many opportunities, even within teaching settings, (1) to ground exhortations for maturity of believers in gospel truth, as Peter and Paul modeled, and (2) to draw connections between taught material and the expected response for both believers and unbelievers. Thus, a teaching ministry in the church context can very naturally include gospel proclamation. The danger to avoid is in failing to challenge believers to grow past basic gospel truths:
Therefore leaving the elementary teaching about the Christ, let us press on to maturity, not laying again a foundation of repentance from dead works and of faith toward God, of instruction about washings and the laying on of hands, and the resurrection of the dead and eternal judgment (Heb 6:1-2)…
When engaging with brothers and sisters in Christ, if we are not prioritizing growth to maturity, then we are missing the point of what is expected even of new believers: to be transformed by the renewing of our minds (Rom 12:1-2), to set the mind on things above (Col 3:1-4), and to allow the word of Christ to dwell in us (Col 3:16), just to name a few aspects. These points reflect the development of the ability to handle solid food, rather than a continuing dependence on milk (1 Cor 3:2).