Since the early days of the catholic Church, the faithful have always kneeled and kissed the ring of the Church authorities. This traditional courtesy reflects the beliefs that:
i. the Pope who is the apostolic successor of the Church instituted by Jesus on earth;
ii. the Cardinals who are Princes of the Church; and
iii. the Bishops who are the local Shepherds of the Church, appointed by the Pope himself,
are all priests through who Jesus Christ manifest Himself to lead His Church. By kneeling before these Christ chosen representives and kissing their rings, (the symbol of authority), one acknowledges their appointments by Christ Himself and show respect to Jesus who dwells in them.
This symbolic gesture of respect toward an authority is no different than when Americans rise when their President enter a room, or when the British rise when the Queen of England enters a room, or when those present rise when a Judge enters the Court Room, or when the Head of any State enters a room.