Of course the author is comparing oklahoma to heaven. The author is saying that oklahoma is second only to heaven. That there are a lot of spectacular places in the world (Spain, England, Vegas)...but none compare to his home of oklahoma besides heaven. That he has been gone for so long that he has forgotten all but that oklahoma is most certainly second only to heaven. The closing of the chorus indicates that he has given up on ever returning to his home but will always remember nonetheless.
Of course the author is comparing oklahoma to heaven. The author is saying that oklahoma is second only to heaven. That there are a lot of spectacular places in the world (Spain, England, Vegas)...but none compare to his home of oklahoma besides heaven. That he has been gone for so long that he has forgotten all but that oklahoma is most certainly second only to heaven. The closing of the chorus indicates that he has given up on ever returning to his home but will always remember nonetheless.