MPs will vote on replacing the ageing submarines carrying the Trident nuclear missiles on July 18.
The proposal is widely expected to pass despite divisions on the issue in the Labour Party and the objection of SNP members.
The Bishops of Scotland have called on the UK Government to honour its commitment as a key signatory to the Nuclear Non-Proliferations Treaty which works towards nuclear disarmament.
In a statement Scotland's eight Catholic Bishops blasted the "immorality of the use of strategic nuclear weapons" that were an "indiscriminate destruction of innocent human life".
It said: "The renewal of Trident is questioned not just by those concerned with the morality of nuclear weapons themselves but also by those concerned about the use of scarce financial resources.
"Lives are being lost now because money that could be spent on the needy and the poor is tied up in nuclear arsenals.
"We endorse the words of Pope Francis 'spending on nuclear weapons squanders the wealth of nations'.
"Britain should take more decisive and courageous steps to revive that aspect of the treaty and not seek to prolong the status quo."