If an anxious Christian were to ask me, "But...but how do you find meaning and purpose without God..." or the similar "But...but how can you have hope without god...?" I'd say, "I don't find meaning or purpose! I don't have hope! I don't need those commodities! Don't want 'em."
These three attitudes point away from Here, direct us away from Now. Here is only of use if it leads to something in the future. Now is only of use if it points to some other thing. Hope is wishing for a never-never-land of some other condition or circumstance.
Why on earth would an atheist have hope for finding meaning and purpose? Here we are, right now!
And yes, sometimes here and now really sucks! I've been there! Big time!
But hoping doesn't help. And trying to find meaning and purpose in misery doesn't fix anything. Better to make the effort to improve here and now than to try to escape via pie in the sky.
Laurance