As a "sceptical theist" and new member of SoF, I proffer the following viewpoint in the hope of cliciting alternative ones.
Faith may be both inspiring and motivating, but is only differentiated from credulity by both the credibility of the beliefs held and the account taken of relevant facts; the former is highly subjective, the latter less so.
The most glaringly obvious fact is the existence of the physical universe, and the manifest inability of any (so far) known "natural" physical laws to account for it. In response to that fundamental problem, a number of approaches are possible, and most have been tried.
The fact that there is a problem can be denied, on the grounds that the objective existence is only a working hypothesis of dubious philosophical validity. This requires a willingness to tolerate distressingly high levels of insecurity, and either a capacity to overcome the resultant reluctance to do anything as concrete as work, or the possession of private means. For most of us toilers, it is probably a philosophical bridge too far.
Ultra-materialists seek to define the problem away, on the grounds that anything we can speak of only came into being with the universe, so that it is meaningless to discuss a cause. Anyone who finds this to be a satisfactory resolution of the problem presumably would not have too many difficulties with even the most abstruse dogma anyway.
Judging by their words (Sea of Faith, April 1995), the authors of the 1933 Religious Humanists' Manifesto hoped to make the problem disappear in a semantic smoke-screen. How does "the universe self-exists" differ from "the universe exists", and how does the statement of a proposition represent any kind of justification for a belief in it?
In contrast, a "basic theism" approach at least faces the issue and has some force of logic: if there is no "natural" explanation, a "supernatural" agency must be involved.
Of course there is an enormous, perhaps unbridgeable, gap between such "basic theism" and the complex edifice of dogma constituting a full-blown religion, which indeed bears every sign of being the product of human invention (not least the fact that they contradict each other).
But the division between those who believe that there is an objective, non-material, "supernatural" reality, of which the physical universe is only a part, and those who do not, is surely the critical one, and everything else is detail.
Such a belief cannot legitimately be challenged by arguments concerning the nature of the "supernatural" agency (i.e. if God exists, how is it that He allows atrocities, etc?). An agency capable of creating the universe is unlikely to be readily understandable.
On the other hand, it can be supported on the grounds that at every major boundary of human knowledge there appears to be a paradox: the "big bang" of cosmology, the elusive nature of the basic constituents of matter in particle physics, and the unresolved problems of mind/body duality, consciousness and free will. It is worth noting that entirely sober, respected physicists have put forward the "many worlds" theory, whereby an infinity of "parallel universes" is deemed to exist, to allow all possible outcomes of physical events, all of which quantum mechanics indicates to be governed by the law of probability. Clearly religion and philosophy do not have a monopoly on difficult concepts, and atheism provides no solutions.
It could be argued that such a belief is too abstract and remote to have any practical significance; but in choosing a way-of-life, it makes all the difference whether we strive to divine a Divine Purpose, or settle for a purely human concensus.
Ultimately, both theism and atheism are exactly equivalent acts of faith, since neither can be "proved"; but theism at least takes a stand on the fundamental paradoxes, and thereby is the more credible of the two.