The government's argument for keeping an "independent nuclear deterrent" is flawed, MPs have been told.
The operational end of Trident's life is due to be 2024
Anti-nuclear campaigners said there was no evidence weapons were a deterrent - rather they increased danger to the UK.
CND vice president Bruce Kent told the Commons Defence Select Committee the White Paper on the future of Trident was unimaginative and disappointing.
He added there was little chance of the UK persuading others not to develop weapons, while it continued with them.
"For us to pursue nuclear security is actually a green light for other countries to pursue the same road," he said.
'Unwise and dangerous'
The lifespan of the Trident missile system's submarines ends in 2024, so ministers say a decision is needed now on its future, to ensure any replacement is ready by 2024.
Tony Blair has said it would be "dangerous" for the UK to give up its nuclear weapons and wants to develop a new generation of submarines.
MPs will vote on the plans in March after a period of debate on the White Paper The Future of the UK's Nuclear Deterrent.
TRIDENT MISSILE SYSTEM
Missile length: 44ft (13m)
Weight: 130,000lb (58,500kg)
Diameter: 74 inches (1.9m)
Range: More than 4,600 miles (7,400km)
Power plant: Three stage solid propellant rocket
Cost: £16.8m ($29.1m) per missile
Source: Federation of American Scientists
But Di McDonald, of peace campaigners the Nuclear Information Service, said White Paper was confusing, using the word "deterrent" 170 times, when what was actually meant was "nuclear weapons".
"I can't cope with this idea of the words deterrent and weapons being interchangeable because they're not. Deterrence is not a weapon - it's an unproven theory it's a past doctrine... It's essentially flawed."
She told MPs capital punishment had been abolished, but there had not been a "rush of murders on the street".
And Mr Kent said there were 182 countries which did not have nuclear weapons yet did not live in "terror and fear because they are about to be attacked by someone".
There was also some scepticism about the proposal to scale down the number of nuclear weapons from just under 200 to 160.
Ms McDonald said it was "no offer at all" because figures from monitoring group Nuke Watch showed the warheads had already been reduced - probably for logistical or manufacturing reasons.
John Ainslie, of the Scottish CND group, said it was important to strengthen the "taboo" attached to using nuclear weapons - "us using the arguments that are in the white paper is undermining that".
The committee questioned whether it was wise to give up nuclear weapons, at a time when Iran and North Korea wanted to develop their own nuclear capability.
But Mr Kent said: "It's exactly the right time to start getting those countries round the table, how can we possibly lecture those countries about acquiring nuclear weapons while we're in the process of saying they're essential for our security?"
Launching the White Paper in December, Mr Blair denied that Britain was under an obligation to disarm under the nuclear non-proliferation treaty and pointed out that new threats were posed by states like North Korea.
"In these circumstances it would be unwise and dangerous for Britain, alone of any of the nuclear powers, to give up its independent nuclear deterrent," he told MPs.