For the Jew or the Christian, this world and its logos, as creatures of the Good himself, are likewise fundamentally good, and so conformity to that logos can possibly be righteous. There is for them a Way of Heaven, a Tao, that pervades the Earth, forms and guides her and all her denizens as she moves in and with it; a Way to which they may, and indeed ought, to aspire. Such folks have a shot at holiness themselves. So we sometimes find them taking that shot, and trying to be good.
For the gnostic, no such luck. Having rejected the creator of this world, and classed him among the evil ones, there is no way that a gnostic can consistently understand the order of his world as intelligibly good. Nor therefore can he believe that agreement with this world’s corrupt order is somehow good or righteous, let alone holy.
The modern gnostic does not of course believe in the fantastic panoply of gods proposed by ancient gnosticism. He is an atheist. But this leaves him in the same basic predicament as the ancient gnostics, for if there is no God, then there is no divinely created or therefore sanctioned order out there to begin with.
For the gnostic, the order of this world is either evil or, in the case of the atheist, entirely adventitious, which is to say, random and meaningless. Holiness and righteousness are concepts that are simply inapposite to such a world, if so we may call it (as, properly speaking, we may not).
The gnostic cannot be holy, no matter what he does. Everything is dirty to a gnostic, and so he has no way of attaining purity. The only purity to be had for him is via the rejection of creation and its order, root and branch.
Further, any system of ordering and classifying reality that the modern gnostic encounters, he must reject as unfounded and therefore unjust. Any such system must impose upon him some obligation or other, more or less discomfiting. This is just in the nature of systematic models per se: they constrain thought, ergo action – or else, they are devoid of meaningful content. To the gnostic, such impositions, as unjustified, cannot but be outrageous. So he rejects his own patrimonial system of order and purity, and valorizes instead some Other. But then he rejects also any jot of influence upon him of that Other that goes any deeper than his vague gesture of distant nominal respect – for any such influence would be but another sort of unjust constraint. He cannot admit that any Others have any consequences for how he lives, or ought to.
So can he say that he tolerates all religions, for to him they must all be meaningless, except for his own gnosticism. And as soon as gnosticism becomes predominant in him, it must then turn and devour itself. For to the gnostic, who rejects all the orders of this world, no system of discrimination, no ukase that this may be tolerated but not that, can in the end be tolerated – not even that of gnosticism. When you reject the world and all that is in it, you reject that rejection in the bargain. If gnosticism is right in its insistence that the world is no good, then neither is that feature of the world known as gnosticism any good.
For the atheist gnostic, there is no safe harbor anywhere in life. Yet we are so made as to want purity and righteousness, and to feel their lack as a painful defect of existence. We cannot rest until we reach a place worthy of rest. But in a wholly bad or meaningless universe, there can be no such place.
This is why the Overton Window must always move. It cannot ever rest.
So gnosticism tends to nihilism, and to despair, and to hatred.