No, an atheists life is not devoid of meaning, purpose or happiness. Perhaps to some extent to an individual, but it's definitely not applicable to the collective. We're a diverse lot, unified only by our lack of belief in deities and don't deserve to be thrown together under one heading. Atheism isn't a world view, only a part of one and us
godless heathens come in large variety of flavours. On I go...
Firstly, the word "meaning" is useless unless you specify and define what you're referring to. It's a human construct and will probably differ with each individual. To get the ball rolling, I will assume the (vague) definition of it being ones subjective value and perception.
That's pretty simple. We all perceive the world differently. We have different memories and experiences and prioritize these according to the emotional impact they had on us. If multiple people read the same book, each person will grasp certain details and correlations that pass over another, purely because those specifics happen to have meaning for that particular person. It's entirely subjective; derived from the context of their life and weaved from a complex matrix of interlocking factors.
Biologically speaking, us humans are compulsively drawn towards patterns. We
instinctively search for disparities and form parallels between them in order to make it more appealing and understandable. To quote Richard Dawkins; the human mind is an "inveterate analogizer". We habitually find meaning in slight similarities between drastically different situations. We have a tendency to focus on particular details (subjectively prioritized) in order to extrapolate the full picture and then further connect the dots along the way with our neat, patterned and "meaning"-saturated lines.
And that's why "meaning" is merely a construct of the mind. We're drawn to it likes flies to honey. Christians, or any theist for that matter, don't get to preside over a monopoly on meaning, despite their self-proclamations. We all get a slice, whether we want to or not.
What would god add to the equation?
How meaningless must ones life be, in order to need a "higher being" to give it meaning? If you depend upon a celestial skydaddy to enrichen your life, your life can't be all that meaningful. Meaning is what you extract from your life and surroundings. It's an entirely personal discovery. You acquire it from your memories, experiences and from the people who you love and consider close. What is meaningful and special to you, is what essentially offers your life meaning. Your the one with the chisel, not any ethereal, invisible being.
I, for definite, don't need any imposed meaning in my life. I'm perfectly content with the universe being without a predefined path or purpose. What could an absolute god-given meaning possibly add to the equation, anyway? Nothing! It makes no difference. Your life is still defined by the inter-connections of reality; your beliefs, perceptions, environment and those people that you meet and depend on. Your happiness and "meaning" is still the derivative of those things, along with many other factors. Throw god in and the only thing that changes is that there's an oddly powerful creator who may or may not require submission and pampering by worship. The balance remains the same: god adds zero.
So, thanks for the offer of "divine purpose", theists - but no thank you.
Reality will suffice.