Brains in a Jar versus All Life is a Dream... Doesn't really matter. In the grand scheme of things if it should happen that pure sollipsism is fundamentally correct (with respect to all perception of reality as we know it), then all observations we make about "reality" become irrelevant. If this "dream world" matters at all it is only to make "life" bearable. Speculating as to how something like "brain in jar" or "all life is a dream" could possibly come to pass are all predicated on our experiences and knowledge of this reality. The net result here is that since everything we know or can speculate is predicated on laws and features of existence which do not actually "exist" under the presupposed sollipsistic scenarios we, therefore, cannot actually know anything beyond basic tautological truisms (if I exist, then I exist).
Religion (organized practice of spirituality with specialized rituals overseen by popularly or dogmatically determined leadership) is almost certainly a weakness. The problem here is that many people seem to assume that all practice of spirituality must necessarily be a weakness if religious practice is a weakness. This is not just illogical; its fundamentally incorrect. It is an empirical fact that throughout history (and even in modern day) that there are numerous men and women of strength that were/are highly spiritual (religious might be the word we would use, but I wish dissociate from organized practice). As this is the case: spirituality cannot possibly be a weakness if formidable individuals can still be produced, furthermore it should be noted that a great many of these formidable individuals counted their faith as a source of strength.
Religion attempts unify the satisfaction of two basic human needs: curiosity and community. For early Man (humankind for the politically correct) explaining the world around Him and ensuring communal bonds meant a large increase in security (both intellectual, emotional, and physical). This is highly adaptive for humans living in a world where survival is "uncertain" (just look at life expectancies to see what I mean). The problems that arose are a function of being too far removed from the people and the original purpose of the institution. The institution has taken on a "life of its own" so to speak. As such leaders can/will make decisions that spark wars, rewrite canon that displeases them, and/or find means of exploiting their followers. The problem doesn't rest with the congregation or community; it rests with the simple human fact that humans will tend to believe and act as their community does; a fact that corrupt leaders have exploited throughout history.
As far as God or other spiritual agencies are concerned: I dare anyone to try and argue that we are the lone intelligence in this universe (let alone multiverse). I dare anyone to argue that our universe is not a wildly mysterious place with innumerable things that we, have not only no knoweldge of but have no conception of. And finally I dare anyone to try and convince me that beings/entities of a nature fundamentally superior (of a higher order of existence) to us do not co-exist with us even now (in case this doesn't seem like a daunting proposition to some of you: consider that 60 years ago a stealth bomber could have flown over the United States and gone pretty much completely undetected. If 50-60 years of technological difference makes that much difference when the body of scientific knowledge doubles every 10 years, then what do you suppose a million years of difference does? Even considering prodiguous periods of dark age, a 500,000 year difference amounts to a numerical difference so vast as to be almost completely incomprehensible...). If you take what we know about the universe/reality and divide it by what we don't know, then you get zero (this is what top scientists, especially physicists and cosmologists will tell you: anything divided by infinity is zero). The long and short of it is: reality/the universe is so complex and mysterious that making absolute claims about what isn't so almost absolutely ensures that you are wrong. Make a claim about what is correct (according to what is known) and you are probably right. Make a claim about what is not correct and just about anything short of outright contradiction is bound to be wrong. The universe/reality is just that wildly awesome, mysterious, and ridiculous.
Side Note: Congratulations to the Catholic church for trying to reconcile with the times, but there is a problem. God exists in mystery; as such giving up ideological room to fact necessarily diminishes God. Either the church needs to present a 100% certain description that it believes immune to change or it needs to concede that their beliefs are human in origin.
If reality is infinite in extent (that is there exists no boundary to all that is; one could potentially delve the depths of reality indefinitely), then how is reality not synonymous with God? Note: I am not talking about Jehovah; I am talking about the perfect being that is motivator of existence.
If reality is "limited" in extent, but eternal (always has existed and always will), then here again how is this not God? Transcending changes of all kinds (superceding time itself): what else but God could do so?
If reality is "limited" in extent and had a temporal beginning point, then necessarily at some point there was a "time" where reality did not exist. This means that there was "nothing." Thus in order for reality to come to be some thing must have created something from nothing. This violates more than just science. Passing on a quality that one does not possess is a contradiction. Nothing definitionally lacks all qualities. So this leaves one possibility: something which can encompass infinite contradictions (creation of all things from nothing) must have created reality: God.
Every effect requires a cause and vice versa where ever anything short of perfection is involved (the cause and effect may very well be seperated by temporal, spatial, conceptual, dimensional, physical, or probability barriers that we are unable to surmount, but they must exist in tandem); any time a transfer or copying of a quality/facet/feature of existence takes place, then something must be the agent of that event and something must be the recipient. This necessarily means all things in reality can be explained (up until you attempt to explain reality itself whereupon logic, experience, and our imaginations fail utterly). Of course once you invoke perfection all bets are off. Perfection can very well be its own source. God is the ultimate cause of God. Reality is unto itself. God and Reality are very likely synonymous if we are just able to test its true boundaries/unboundedness.
Note: I realize that pretty much none of what I said above amounts to faith. I reject arguments from design (beauty is far too subjective and order necessary to a certain extent in order for things to exist, so even if Jehovah didn't exist order would be purely necessary to for things to be as they are). I reject arguments that intelligent design is just a camouflage for Creationism exactly because ET and the Great Spaghetti Monster are just as valid explanations for the universe under intelligent design as God is.
In the grand scheme of things faith is a personal thing and like all things we are aware of, too much of it is a bad thing. Everything in moderation, including moderation. Taken too far (or without the proper balancing traits) anything becomes dangerous; faith becomes fanaticism and blindness. But does this mean that faith cannot be a virtue? Not by a long shot. Too much trust; too much love; too much happiness; too much honor; too much compassion can all lead to problems a person if they exist in isolation. Faith isn't necessary to lead a fruitful existence (I don't think any singular virtue is), but I think anyone would be remiss to think that their life could not be improved by at least a token amount of faith. The question is finding some thing that for you personally is worthy of faith (ideology, entity, fate, karma, yourself...).
MTF