The Rev Sally Foster-Fulton, convener of the Kirk’s church and society council, is among a number of co-signatories to an open letter from the campaign group Child Soldiers International, calling for an end to recruitment of under-18s to the army.
The MoD currently enlists soldiers at 16 and deploys them from the age of 18.
In a letter addressed to defence minister Mark Francois, the group of signatories said: “We commend the MoD for having ceased routinely deploying children into conflict, but challenge its failure to stop recruiting them.
“Current recruitment policy channels the youngest, most disadvantaged recruits into the most dangerous frontline combat roles.
“Those recruited at 16 have faced double the risk of fatality of adult recruits in Afghanistan.”
Ms Foster-Fulton said that they wanted to “protect the vulnerable”.
“The Church, through its forces chaplains who stand by those on the frontlines of battle, knows the brutal reality of war,” she said. “It is that experience that informs our belief that the recruitment age should be raised, for our sakes, not just those whose young lives could be cut short because we were not brave enough to make this change.”
She added that it remained “everybody’s responsibility” that young people should have the opportunity to make the best of themselves and not be asked to face “an impossible choice” between “poverty and the possibility of death far from their families and friends”.
Other signatories include all the bishops from the Church in Wales and peace groups run by Christians including Baptists, Methodists, Roman Catholics and Quakers.
Even during the First World War, the minimum recruitment age was 18, and only those aged 19 or over were sent overseas to fight, the letter said, although it was known that many younger boys slipped through.
Child Soldiers International said its own analysis of MoD figures showed that last year 880 16-year-olds enlisted in the army, 40 per cent fewer than the year before and just a quarter of the 3,600 enlisted a decade earlier.
The fall has been matched by increasing drop-out rates, the group claimed.
Figures recently released showed that nearly half  of under-16s left during training.
Richard Clarke, director of Child Soldiers International, said: “Army training does not give young people what they need to succeed in today’s economy, especially in terms of qualifications.”
An MoD spokeswoman said that the letter had ignored the benefits and opportunities that a military career offered young people, adding: “It provides them challenging and constructive education, training and employment, equipping them with valuable and transferable skills for life.”