God's plan from the Scriptures: preparing a people, becoming incarnate among them, empowering them to tell others so that the message permeates around the world. More than once I've wondered why this seems so inefficient. Why do missionaries have to struggle with learning languages, applying for visas and finding money for airfares?
What do we see in Acts? Among other things, we see the Spirit gifting people with instant ability in a foreign language (Pentecost), and we see the Spirit transporting Philip instantly across a distance of several miles. (Acts 8:39-40). If these two miracles were more common, the two biggest hassles of missionary existence would be solved. Why does God not choose to work that way? Surely every people group could have been reached by the Gospel within two or three centuries after Pentecost. Perhaps even sooner?
I've thought of an even more rapid plan than that. Suppose God the Son had chosen to become incarnate as Abel? Abel could have formed one or two disciples, told them he was not just a son of Adam, but the Son of God, performed miracles, told them he would lay down his life for their sins, and then be murdered by Cain. Abel comes back to life, tells his disciples to tell everyone what he had done, and ascends into heaven. How many people exist to be preached to? Maybe less than ten, maybe forty maybe perhaps even a hundred. This depends on your view of how many children Adam and Eve had that weren't mentioned, plus how many children they had. Potentially the Gospel of salvation could have been preached to every human on earth at one family reunion. Or maybe it would have taken longer (Cain perhaps was anti-social for a while there). But this whole messy period of the Kingdom of God coming into human history but not fully present yet could have only lasted a year, or a few years.
So why didn't God choose to work this way? Obviously I don't have the full answer. But one thing does come to mind as I write this down. In either of my efficient scenarios, I wouldn't be here. Since in heaven we are like the angels, not marrying, I assume that means we don't have children either. So if Christ returned centuries ago and brought in the fullness of the Kingdom, I would never have been born. So I guess that's at least one argument for the "inefficient" mode.
The last verse of Hebrews 11 says that God had planned something better for "us" (the original readers of Hebrews) so that only together with "us" would the heroes of the Old Testament be made perfect. I'm guessing the same logic applies. In God's plan, only together with us twenty-first century folks, will the Apostles and Augustine and Wesley and Townsend be made perfect.