I'm an agnostic (absolute, textbook definition) but I disagree. As a human with consciousness and free will (whether that's an "illusion" doesn't make a difference from where I'm standing), I define meaning in my life. Not all consciously, but I have thoughts and desires. If it'll all be irrelevant when I die, why should I care? I'm not dead yet. If there is no afterlife, I won't be around to care. If there is, I'll figure it out on the fly.