In the film, posted by American social media evangelist Joshua Feuerstein, the woman challenges her dentist on why he doesn't believe god is real, replying that she "doesn't believe in dentists".
Her dentist says that he doesn't believe god exists, because of all of the suffering in the world, but the woman tries to counter his argument by saying: "If there are dentists in the world, then why are there so many broken, infected and missing teeth?"
The video has been shared over 59,000 times on Facebook since it was uploaded by Feuerstein, who once offered a $100,000 reward to anyone who could prove that god didn't exist.
The Arizona-based evangelist - who has more than one million likes on Facebook - uploaded the video in December but it has been re-shared this week.
Richard Dawkins, one of Britain's best known atheists, told the Huffington Post UK: "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."
Feurstein is a former Christian pastor, television evangelist and social media personality who posts religious videos with the hastag #ShareIfYouCare. Posting the dentist video, he commented: "Someone give GOD a SHOUTOUT!"
When Feuerstein released a video a video last May that claimed to "demolish evolution" in three minutes, Dawkins posted a detailed rebuke of the ex-pastor's argument on his website, calling it "unfathomably arrogant pretension for somebody who tries to sound humble by calling himself a nobody in his twitter bio."
Dawkins wrote of his surprise that: "Somehow people aren’t writing this guy off as someone with delusions of grandeur. No, plenty of religious people are sharing this around as though they agree that this man has unsettled the discipline of biology.
"I humbly suggest that if you’re going to this guy for your science and not to, well, scientists, you probably don’t care an awful lot about science (until it’s saving your life or making porn free and easily accessible)."
Many people have attacked Feuerstein's dentist video on Facebook this week. One commenter, Dylan Clayto, said: "This didn't "destroy" atheism at all. Don't get me wrong, I'm an agnostic theist and I love listening to all religious opinions with an open mind, but this video in NO way "destroyed" atheism. Sure, it makes perfect sense that God won't help those who don't seek help from him, but that doesn't prove his existence."
Another man, Hunter Hansenm said: "The difference between a god and a dentist... is that anyone can see dentists, visit dentists, become dentists, talk to dentists, and substantiate that such people as dentists even exist. You can't do any of that with "god."
"It's sad to see people engulfed in that level of stupidity," he concluded.
Others supported the video, with commenter Alifereti Drodrolagi Uluisuva simply saying: "In your face atheist".
Rayner Bettesworth, a Christian, posted: "It is interesting to see the amount of atheists always trashing a Christian post. You don't really see that Christians trash atheist posts... but I can understand that it is quite depressing to live for nothing else in this world but to just die one day. So trashing Christian pages makes them feel better about life? Shame."