God often uses our faith to do a miracle, in our life. Jesus could heal the servant because of his compassion, but obviously, what God was looking, was the participation of the man, in the act of God, by his faith.
Very often, God seems to do miracles, together with us, with our involvement, by our faith. That is why Jesus said to the man ‘May it be done to you, as you believe’.
God did not want to heal his servant, and let the centurion just sit around, and be a spectator, watching how Jesus would perform the healing. He wanted to do the miracle together with the participation and involvement of the centurion by his faith.
Of course Jesus could heal his servant by himself, and let the man just watch, and be a spectator. But God choose to involve the man in the performance of the miracle, by using the man’s faith. Perhaps in that way, God wanted to grow the faith of the centurion. It was like Jesus was saying, ‘Let us do the miracle together’.
Our faith in God and the miracles he does in our life, validates and shows respect towards the actions of God in our life, and the miracles he does. When God uses our own faith in him, to do a miracle, our faith is the respecting part of the miracle of God.
If God did just the miracle without involving us and our faith, which he often does, we would just be the spectators of that miracle, and there would not be our faith involved to the respecting part from our side, for that miracle.
Is it possible that God wants to do a miracle in our life, in the same way, just as he did for the centurion?