The poll by the Pew Research Centre questioned 1,546 adults aged 21-26 and asked them about a range of things they expected to happen by 2050.
They found 71 per cent expect cancer will be cured, 66 per cent expect artificial limbs to be working better than real ones and 53 per cent say ordinary people will travel in space.
But it was the high number who confidently predict a Second Coming that raised eyebrows.
David Silverman, spokesman for American Atheists, blamed poor education and ignorance.
He said: 'This just shows how ignorant people are and that our school system does not teach critical thinking, something that Britain does.
'I am not so sure the figure is that high as some people will say they believe in God when they don't really believe at all.
'My prediction is that by 2050 that number will have shrunk significantly. We are not a more religious nation, we are a more brainwashed nation.
'If religion challenges school governors they cave in and roll over, that does not happen so much in Britain.'
He added: 'They have been saying Jesus will return for 2,000 years, and I'm sure they will be saying he will return for the next 2,000'.
In Britain the situation is much different and while many call themselves Christians if asked, church membership has been declining steadily.
The latest British Social Attitudes Survey's report showed that those calling themselves non-religious rose from 31 per cent to 43 per cent between 1983 and 2008.
A survey last year showed that two thirds of teenagers don't believe in God at all.
Those who replied to the survey said that family, friends, money, music and even reality television are more important than religion.
Some six out of ten 10 children also believe that religion 'has a negative influence on the world'.