We are nearing an age when we can confidently say that all the world’s people groups have experienced some sort of gospel engagement—someone has crossed a cultural barrier to introduce a particular people group to Jesus, the gospel has been made available digitally, etc. Yet over 3 billion of the 8 billion people in the world still live within “unreached” people groups. Beachheads have been established, but there are still not nearly enough churches, missionaries, and individual Christians within these people groups to be able to reach their entire populations for Christ. This can be characterized as the missional gap.

A missional gap exists in the United States, and other places in which the gospel is widely accessible as well. For the US alone, 44 percent of the population qualifies as “post-Christian,” and we have the fifth largest non-Christian population in the world. In Unwavering Resolve, Dave Robinson, executive director of Cru®’s US Church Movements ministry, labels the United States as a rejected access nation—possibly the first in the history of Christianity.

The burden of these missional gaps fueled the writing of Unwavering Resolve. Closing the gaps requires the launching of many more thriving spiritual movements where Christ is made known, young believers grow in vibrant faith, and these new Christians multiply themselves so that more and more people can hear about Christ and learn to follow Him. This requires apostolic leadership. Unwavering Resolve defines this crucial leadership role and establishes a theologically rooted, practically applicable job description for apostolic leaders that flows from the heart of Jesus and the life of Paul. This is an essential guide church planters, missionaries, sending agencies, pastors, and their teams will return to again and again for inspiration and guidance.