The evil propaganda of metaphysical personal insignificance

When looking back across what is known of human history; it is notable that whatever was the official and established religion of the past, and whatever is the atheistic materialism of the present - almost all of them share a fundamental, metaphysical, assumption that individual people are insignificant in the context of total reality. 

All these systems of religion or ideology seem to be united in an insistence that individual human beings cannot make any difference to the Big Picture in the Long Term.

Nonetheless, despite that individuals make no difference whatever they think/ say/ do - the conclusion is drawn that it is a sin, or dumb, or an insane delusion - but certainly a Bad Thing - if or when an individual believes that he does or can make a difference to eternal reality. 

What is recommended of each individual is always to recognize and accept his own ultimate insignificance; and therefore to strive for something like humility, servitude, obedience, self-abnegation. 

Despite vast differences between religions, and between religion and no-religion, and between ideologies - it is striking how they all nearly-always converge on this same assertion: 

"Ultimately, you don't matter. You need to accept this as a fact, and live accordingly."

So many millennia of anti-individual propaganda, hammering down on us throughout our lives, is indirect evidence that we have contrary innate, spontaneous, and instinctual conviction that we are personally significant, and we do matter as individuals; and that what we think, say and do can makes a difference to the Big Picture - and permanently. 

And that this difference may be positive. 

There is, I suggest, an inbuilt assumption that we personally and alone can potentially make total-reality Better. 

I don't think we need persuading of this, because it is a given. 

But we do need some kind of metaphysical explanation of how this could be true...*

(i.e. An explanation of just how I personally could contribute something unique, irreplaceable, and positive; to eternal reality.)

We need this especially; given that all the society-wide and available metaphysical explanations of history seem to be dedicated to explaining how we personally are necessarily insignificant, and therefore cannot make any difference to reality...

(Or - maybe - explaining that, by believing in our personal significance and trying to contribute positively, we will necessarily be doing wrong, and making matters worse.)

* An explanation of how it is true that we personally and alone can potentially contribute something positive, unique and eternal to divine creation; is a thing that my metaphysical assumptions and Christian theology intends to accomplish: to my own satisfaction, at least!