Richard Dawkins has dismissed a Christian video that claims to undo atheist reasoning about God, saying the argument was "pathetic".

In the video a woman tells a dentist that saying you don't believe in God because of suffering in the world is like saying you don't believe in dentists because some people have bad teeth.

"If there are dentists in the world, then why are there so many broken, infected and missing teeth?" the woman asks.

The dentist replies: "I can't help people that don't come to me to have their teeth fixed."

Evangelist Joshua Feuerstein shared the video with his million plus Facebook followers in December, but the video has had renewed interest this month.

Speaking to the Huffington Post, Dawkins said: "If this is the best the faith-heads can do by way of 'demolishing atheism', I hope you will give it maximum publicity in order to demonstrate how pathetic the 'argument' is. It's so weak, no reply is needed. To anyone of any intelligence at all, it replies to itself."

This isn't the first time Dawkins has responded to Feuerstein's claims to unpick atheism. The Arizona-based evangelist shared a three-minute video in May last year in which he said he would "demolish evolution" in three minutes. Dawkins subsequently wrote a detailed rebuttal of Feuserstein's arguments in a post on his website.

Dawkins wrote: "Everybody and their grandma is sending me this clip of some random guy in a facebook video who claims to destroy almost the entire field of biology in three minutes. No studies, no experiments, no peer review, no degree (undergrad or otherwise) in biology, just chillin' in the back of a car taking a selfie. This is an unfathomably arrogant pretension for somebody who tries to sound humble by calling himself a nobody in his twitter bio. But then again, apologists have never been renowned for their humility."

The evolutionary biologist continued with an 18-point critique of the evangelist's arguments.