We are told to pray to God, “Your will be done on earth.” We’re to ask God, “Give us this day our daily bread.” And there should be prayers to God to “send forth laborers into His harvest.”
These examples of prayer are obviously God’s will; what He wants to happen. Since God is God, though, can’t He do these things without them being prayed for? Yes!
But, it is Jesus Himself who instructs us to pray for these things (Matt. 6: 10, 11; 9: 38). So that tells me that it is apparently God’s preference, His method of operation, to work through the prayers of His human creation.
Another example I think about is in Ezekiel 22: 30, in which God searched for someone to stand in the gap between Him and the sins of Israel. God was looking for someone to pray that His wrath not be carried out.
But why would God put the responsibility on His people to bring forth His will? The answer is probably rooted in the authority that God gave mankind in the beginning of earth’s history. Dominion over the earth was given to us. We are meant to be God’s representative on this planet. What happens on earth is dependent on us—its overseers.
God, being a God of order, certainly is a respecter of His own decision to put us in charge. So naturally He would have His will, in the spiritual, be carried out in the physical realm by His delegated representatives – earth’s supervisors – who ask for it.
God works through the prayers of His people. He doesn’t desire to work independently of us. So is prayer necessary for God’s will to manifest? It must be. After all, remember, Jesus indicates that this is the case.
Therefore, for God’s will in this chain of command to work, we need to ask for it to be done in our and others’ situations and circumstances. For maximum effectiveness, it would be helpful to know what His will is through scripture, and specifically pray for that.
Prayer, it seems, is indeed necessary for the power of God’s will to be released.