|Daniel in the Lion's Den|
This is the Angel Gabriel, the same person who would later announce the coming birth of Jesus (Luke 1:19, 26). He is sometimes called an archangel, but that is just a tradition. That word isn't applied to him in Scripture.
There is no problem for anyone in the idea that an angel would be sent in response to a prayer. In fact, it happens again in the very next chapter of Daniel. However, it is too easy to pass over the fact that this is not what happens in this story.
Rather, Gabriel was sent "at the beginning of [Daniel's] pleas," not after them. When Daniel started to pray, God acted by sending Gabriel. Not reacted. Now we have a problem for the Arminian. How could God have responded before Daniel even prayed what he desired?
This is made even more-explicit by another Prophet (Isaiah 65:24): "Before they call I will answer; while they are yet speaking I will hear." That is, in the earlier Prophet, Jehovah promised exactly what we see taking place in Daniel. But the Arminian cannot explain God's promise, because he believes that men act according to free will. God cannot do something that is contingent on the will of a creature.
However, this experience is completely consistent with Calvinism. The Reformed believer understands that it is God who is sovereign, not the will of man. Therefore, when we pray, we are not informing God of something of which He is not aware, or on which He has not already determined to act. Rather, as in all things, the prayer and His response to it are both according to the predestined purposes of God.
"Why pray if God has already decided what to do?" the Arminian asks. Rather, "Why pray if God does not determine all things?" is the Calvinist's answer. How can a believer have any assurance in prayer if he imagines that God does not know, and is unprepared to address, his need of the moment? That wasn't Daniel's confidence. Rather, our confidence is in that promise from Isaiah, that God knows our needs before we do, and has determined to act before we can even think to ask Him. That is security!