Our Lord came to this earth with all the physical defects of sin. He wasn't like adam 9 ft tall and as broard as a door. When the bible speaks of flesh it is refering to the effects of sin in many cases.
Jesus said himself he would be a sacrifice and in three days he would be ressurected. What about the empty tomb? What about Thomas who said he wanted to place on Jesus wounds?What about when Jesus saw his followers and he asked for fish to eat and declaired a spirit doesn't flesh and bones.
As Jesus body was changed into a spiritual body so we will be changed at the second comming it says in revelation our bodies will be changed into an incorruptual body.
Christianity relys on the ressurection of the body and can be found in the creeds.