How can Athiesm not be taken seriously? It's one of the fastest growing sections of our society and tends to contain the highest percentage of people with higher education. Athiesm is sporting our best and brightest and at a faster rate than ever before.
And what do the religious fanatics have as a basis for their side of any debate? Faith, which is about the least tangible concept one can imagine. Faith, by definition, is a sort of belief with no evidence. The Ancient Greeks spent an awful long time believing in a whole series of gods. There was a god for just about everything from war to poetry to tuna fish sandwiches on rye. They had plenty of faith I am sure, but in time, their ideas became comedic. Just like the mythology of those times, today's religions will pass.
The more we learn about ourselves, our planet, and everything else around us, the less room there is for religion to make up answers to life's questions. Soon this crutch will no longer be needed.
In time, those individuals who belief who believe Athiests to be "America's least trusted group" (see recently published studies) will all die off, and new leaders wiill emerge from the ranks of the younger generation. More and more of those leaders will be enlightened individuals who value actual knowledge over the comfort provided by an imaginary omnipotent caregiver. And it is a simple inevitability that Athiesm will not only be taken seriously, but it will be the norm.
Even our art reflects this somewhat unspoken expectation for human evolution. A seemingly large majority of our book and films that take place in the future contain no reference to religion. It's as if somewhere in the back of everyone's mind is the knowledge that religion will fall to the wayside just like all the primitive unfounded beliefs of our past.
At some point society stopped sacrificing virgins. And at some point society stopped burning witches. Sooner or later we will all be able to let the rest of our "supernatural" beliefs go.
So to ask if Athiesm will be taken seriously is simliar to asking if medicine, or science, or the very air we breathe will be taken seriously. Not only will it be taken seriously, it will eventually be the only thing considered sensible.