Happiness is a highly subjective state? Hell no. A healthy flourishing state of mind and body, self and world is objectively verifiable. Rand did consider introspection an objective means of validation, of objective thought turned inward. And if happiness is not the standard of morality - well that may be a Christian viewpoint, but it is profoundly anti-American and antilife.
And you have no evidence Rand's atheism was primary. She explicitly details why reason and reality are her givens, and that atheism is derived from that.
Lots of words there ... but I'll bet you cannot come up with a single, objective factor that guarantees "happiness" at all times, for all people.
Because, you see, that is what "objective happiness" has to be. It CANNOT vary by individual or by time, because that would make it subjective happiness.
You're propounding a view of happiness that makes it like a feat of engineering: this input must produce "Happiness" as a result."
I'll bet you can't even define "happiness" in a way that is objectively testable!
And you have no evidence Rand's atheism was primary. She explicitly details why reason and reality are her givens, and that atheism is derived from that.
Well, she says that "reason and reality" are her givens ... but her philosophy ends up being neither reasonable nor in contact with reality. Something as real and natural as parenthood crushes her central thesis of self-interest. No parent can morally live as "an end in himself."
One must conclude that Rand chose her premises on some other basis than reason or reality; she clearly wanted to arrive at (most of) the commonly-held set of Western moral principles, but it is just as clear that she needed to find a moral basis other than that which had guided the morality of Western Civilization; i.e., a theistic worldview.
Rand's laughably flawed descriptions of Christian belief are proof enough of her virulently athiest world-view. One gets the impression that her description of toddler Dagny Taggart's tantrum in church is an autobiographical fantasy scene ... we get the impression that Rand has always been an atheist.
When you couple the two points ... yes, it's very reasonable to conclude that Rand's atheism came first.