Here is the biggest reason that I think this... Later in the first verse, the song says, "Within my heart a memory. A perfect love that you gave to me." Who else gives perfect love but God?
Then The chorus is pretty much saying that he can do anything when God is with him.
When you are with me I'm free
I'm careless, I believe
Above all the others we'll fly
This brings tears to my eyes
My Sacrifice
Then, In the second verse it says: "We've seen our share of ups and downs. Oh how quickly life can turn around. In an instant." That means that even though he had lost faith in God, his hope was restored in an instant. "It feels so good to reunite within yourself and within your mind." That means that he is reuniting with God, and inviting him back into his life.
"I just want to say hello again."