2 Chronicles 32:20-21
Now because of this King Hezekiah and the prophet Isaiah, the son of Amoz, prayed and cried out to heaven. Then the LORD sent an angel who cut down every mighty man of valor, leader, and captain in the camp of the king of Assyra. So he returned shamefaced to his own land. And when he had gone into the temple of his god, some of his own offspring struck him down with the sword there.
"Father, thank You for these words, and for the conclusion to this Bible Story we've been looking at. Hezekiah gave encouragment to his soldiers before facing Assyria, reminding them that You were with them. The King of Assyria said that if no other god could save a people, why should You. But You came through for them, just as, if we ask You to, You will come through for us. In Jesus' name, Amen."
So after all of this drama between Judah and Assyria, Hezekiah and Isaiah prayed, and God took care of them. And He didn't just say, 'Oh, I'll kill some Assyrian and a few leaders and make them turn back' or 'I'll turn their hearts away from killing Judah'. He had his angel kill every man, officer and enlisted, in Assyria's camp. Sennacherib was ashamed of how horribly he had lost, and to an angel. He had lost so horribly, his kids killed him. That's pretty bad.
But what was the key to all of this? Hezekiah and Isaiah prayed. They asked God to help them (with a belief in God, knowing He would answer them, et cetera). That's what started all of this, prayer. God will always answer our prayers, as long as:
a. we have a relationship with Christ
b. we believe that He can answer the prayer
c. it's according to God's Will (no asking God for the answer sheet to an opcoming test, because cheating is lying/stealing and against God's Will for our lives).
God knows what's best for us, also. He made us. We may say that we weren't cut out for something, but He cut us out, so He knows what we're built for. If we ask for something that isn't sinful, that applies to all those rules, God will give it to us in His own time, because we need to learn a lesson.
In His Service,