my question is why would Home by Daughtry get airplay on Christian Stations and make it to the charts and not Over you by Daughtry or any other songs?
I absolutely think this is due to the lyrics and the positive message of "Home" - it talks about how you can always get a second chance, and the references to "going home" could be seen as talking about going up to Heaven. (Some old songs refer to this as "going home to see Jesus" as I recall.)
In some ways, I think it is even like "I Can Only Imagine" in that the lyrics refer to "I'm going to the place where love / And feeling good don't ever cost a thing." I can certainly see how this could be referring to the unlimited grace given to us by God as a gift for which we don't have to do anything.