The verses from Acts 19 show a God-ordained pattern. Where the word of God is preached, God's grace finds its target.
And many that believed came, and confessed, and shewed their deeds. Many of them also which used curious arts brought their books together, and burned them before all men: and they counted the price of them, and found it fifty thousand pieces of silver. So mightily grew the word of God and prevailed." -- Acts 19:17-20"And this was known to all the Jews and Greeks also dwelling at Ephesus; and fear fell on them all, and the name of the Lord Jesus was magnified.
As Calvinists, we acknowledge that only those names covered by the blood of Christ, ordained and purposed and determined and predestined by God from before the foundation of the world according to His good pleasure alone and not based on anything inherent within those individuals or any "fee will" choice to believe, will be saved. Election is by grace alone, and not by works which includes even our "good work of faith."
So agreeing on this, we ask ourselves what is God's plan in this world? Is it to save only a few; or is it to keep on bringing in the sheep who will eventually outnumber the wolves?
What did the word of God do? It "grew mightily." And it "prevailed."
I don't think God intends for Christianity to fail. I think God intends for Christianity to succeed and prevail. Here's a short and succinct understanding why premils and amils seem to be giving up the game before the whistle blows...
The next question pertains to the earthly success of this kingdom. Will the kingdom Christ established be successful in history? Will the promised Seed of Abraham really be a blessing to the nations? Will Christians experience success in carrying out Christ's commission to bring the nations under the discipline of God's law? The answers to these questions constitute the only significant difference between the amillennial and the postmillennial positions. In reality, amillennialism is only a type of pessimistic postmillennialism. The amillennialist does not believe that the world as a whole will be discipled. They believe a few from every tribe and nation will be saved, but do not believe that the power of the gospel will result in a "golden age" in history...""...Christ's millennial kingdom (the time between the first and second advent of Christ) will last an indeterminate, but perfect, amount of time.
If you have the time, read North's take here online free...
***The answers to these questions constitute the only significant difference between the amillennial and the postmillennial positions. In reality, amillennialism is only a type of pessimistic postmillennialism. The amillennialist does not believe that the world as a whole will be discipled. They believe a few from every tribe and nation will be saved, but do not believe that the power of the gospel will result in a “golden age” in history...”***
But, this is precisely the Edenesque utopia to which I referred earlier. There is simply some variation into exactly what form this “golden age” will take among postmillennialists. You cited Acts 19 to demonstrate that “mightily grew the word of God and prevailed.” I have no problem with that verse. I was simply pointing out that this prevailing was done by the spread of the gospel on the ground that was wet with the blood of the saints. How, precisely, does a post-mill reconcile such facts with a “golden age,” especially considering that MOST Postmills believe that this golden age will result in bringing all the nations under God’s law?