Hi JFEdgar,
'Verily, verily, I say unto you, He that entereth not by the door into the sheepfold, but climbeth up some other way, the same is a thief and a robber.'
In this passage, I believe Jesus is discussing false shepherds.
I've heard it expounded as if it refers to the ordinary sheep, but recently when I was reading John, the Spirit made me understand a much greater sense to the whole section, if it is simply a dissertion on who is trustworthy and why (or why not). He is giving the Father's perspective on the whole matter, as well as His own.
I think you are right when referred to the robe of righteousness in your first post. The wedding garment is also that of the suffering Church, who is ready and willing to lay down her life for her Lord, who has already laid down His life for her. By this unlikely outcome of the shedding of blood, through Him, her robe is purified until it is holy and without spot, wrinkle or blemish. By her hoping to the end (death) for the salvation which shall be brought to her in the last day, He is vindicated in His sacrifice for her.
hmmhmm, I'm not sure how the man gets into the wedding feast without his garment on. (Apparently the garment is sent in good time for it to be worn on the festive occasion) but, it is also sign that the person has esteemed the host worthy of his humble presence, that he complies with the host's request to wear the robe.
When the man doesn't wear the robe, he is showing he does not respect the host, nor the invitation he received, nor the expense on his behalf of providing a wedding garment specially reserved for him. The invitee is behaving as if the host is beneath his dignity. Little wonder he gets thrown out, then, by the host, the Lord of Glory, who is Righteous, and our righeousness.