Atheists have no reason to live
In some ways you have hit the nail directly on the head. Atheists would tend to say that they are not here for a reason; that nothing is pre-ordained; that there is no divine being who has directed the forces of good and evil (however incompetently). But that is not to say that we don't like to be here and don't want to work for the benefit of the world or for future generations.
A lot of atheists are humanists. In my own case, I still can't quite decide whether I am or not. I do happen to be a strong secularist. That means that I'm happy for you to worship whatever mythical being you like as long as it does affect my life.
That, for me, is a reason to live (even if I have no others). I want to make it possible for other atheists to live without the threat of organised religion. In many parts of the world that is a dream that will not be reached for many decades.
That kind of statement is hardly worthy of a response. It is not exactly well defined; not clear and transparent what it really means.
And of course this is a typical hallmark of organised religion. Its proponents like to keep things vague and transcendental for all sorts of reasons - none of them good!
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