Pete Broadbent, the Bishop of Willesden, north London, described the Royals on his Facebook page as "philanderers" with a record of marriage break-ups who who "cost an arm and a leg".
He also denounced the "nauseating tosh" surrounding the "national flimflam" of the wedding and said the basis of the Monarchy is "corrupt and sexist", the Daily Mail reported.
In his post, which has been criticised as too harsh, the bishop said the wedding should belong to the family and was not "some piece of national flimflam".
"I give the marriage seven years." Referring to the 1981 marriage of Prince Charles and Princess Diana, he added: "I managed to avoid the last disaster in slow motion between Big Ears and the Porcelain Doll, and I hope to avoid this one too."
His comments, which are sure to dismay his immediate superior the Bishop of London, Richard Chartres who is a close friend of Prince Charles, were also condemned as "cruel" and "disrespectful" by MPs and Church members.
Tory MP Nicholas Soames, a friend of Prince Charles denounced the Bishop's comments as "absurd and ridiculous", saying: "They are extremely rude, not what one expects from a bishop."
To add the embarrassment, the row comes just two days before the Queen opens a new session of the General Synod -- the deliberative and legislative body of the Church of England which was instituted in 1970, replacing the Church Assembly.
Synod member and former MP Canon Peter Bruinvels said: "This is deeply disappointing and disrespectful. The Bishop should be reminded that we are an established Church in which the Monarch plays an integral role."
Fellow Synod member Alison Ruoff added the comments were "cruel, childish, unnecessary and unchristian".
The furore could prove particularly embarrassing to Bishop Chartres as Church sources have suggested he may conduct the wedding service -- although it would be a break with tradition not to use the Archbishop of Canterbury, said the report.
Broadbent -- a founder member of the Church's powerful Cabinet, the Archbishops' Council -- first commented on the Royal wedding on his Twitter account shortly after the couple announced their engagement on Tuesday.
The official announcement of UK's much-waited royal wedding came last week following an eight year on and off romance between William, the second-in-line to the British throne, and his longtime companion Middleton.
According to the Clarence House, the wedding will take place in spring or summer of 2011, in London.