The Church of England yesterday strengthened its opposition to the renewal of the Trident nuclear deterrent.
It follows moves by a number of other Christian denominations who have expressed their opposition to Trident.
The Church of England's General Synod ('parliament') voted in favour of a stronger amendment to a motion which already raised "serious questions" about the possible renewal.
The amendment suggests to the Government that the proposed upgrading is contrary "to the spirit of the UK's obligations in international law and the ethical principles underpinning them".
Members of the Synod voted by 165 to 149 for it to replace a more timid phrasing, which asked the Government to think more about how Trident might affect its obligations.
The Archbishop of Canterbury, Dr Rowan Williams, who has already said the renewal poses "grave" ethical questions, joined calls for the Church to send a more robust message.
He said: "I'm slightly sorry that the original motion wasn't rather stronger.
"I support it as a way of putting down a marker about the tactics of modern war, about that category of weapons which cannot be morally approved.
"I believe that the least a Christian body ought to do would be in these circumstances to issue the strongest possible warnings and discouragements to our Government."
The Synod debate was called in advance of a parliamentary vote, expected next month, on whether to order a new generation of weapons at a cost of billions of pounds.
Scottish churches have been particularly vocal in their opposition to Trident renewal, which the government has said it will push through in spite of massive opposition both at home and internationally.