I am sure you have heard of them before. Studies comparing the comparative happiness or charitableness of people across religions, or seeing how such things vary according to church attendance or religiosity, or confidence in one's religious beliefs, or what have you. Even if they are mild, it always seems to show that the most church-going are the most happy with their lives . And, I only bring this up because religion, in this country in particular, has grown beyond simple belief in certain ideas, and is something much more complex than that socially, which serves to confound any claims that you can make about the effects of the beliefs themselves.
Even in an ideal, hypothetical form, non-institutional religion could serve as a social group, defined by a shared set of beliefs on any subject if people grew to agree with the person to originally come up with the ideas that form its core. Of course, in a setting that consists of more than a handful of people, it becomes trivial to call any subject that there is some form of consensus on a religion unless it is of significance to both the bearers of the relevant beliefs and those who do not (and who may or may not hold alternative beliefs). At its heart, this group means nothing more than any other division or label. But, it all depends on the significance that we collectively are willing to give to it, in contrast to other forms of groups. This is the heart of the matter, so let's see how exactly we prioritize organizec religion and its components, and what we associate with it.
Cultural view of the virtue of belief: It is almost inescapable. It is the idea that you cannot be moral without having some form of religious precepts to follow. The idea that those of any religion (especially your own) are better in behavior and lifestyle habits than those who do not have any. Religious beliefs are deemed to be inherently good, and a more or less necessary step for someone to become a good person.
View of church attendance as proof of belief: This perspective has been waning with years (I'll address that later). But, it works alongside with the former one. It is the idea that religiosity correlates with church attendance. Only the most religious attend church everyday, and you are only nominally religious if you only show up to church occasionally. It is up for debate whether those who do not attend a church can call themselves religious or not. When coupled with the former perspective that religiosity is correlated with goodness as well, those who do not attend church may be viewed in a rather poor light. Ironically, if enough people hold the idea that it is inherently bad to miss church, they will influence those around them to attend church more to avoid such suspicions, which further breaks down the very assumptions behind the pressure they are applying, due to the fact that they are driving people to fill up the pews in order to hide either their bad behavior, lack of religious faith, or both. When church attendance becomes a cultural mandate, rather than a self-selecting process, things tend to get muddled.
Sense of community offered by attendance: This is a natural implication of church being a social group that meets independent of the constraints of a much larger society. It offers a connection to other people, and since it is a connection that is not limited to mere geographic proximity, but ideological similarity as well, it may actually be a more powerful form of connectedness and community than one could necessarily find in a neighborhood, workplace, or school. This is of significance in a few ways, which will be addressed shortly.
View that belief leads to charity: This may or may not be related to the idea that belief is in of itself virtuous, or conducive to virtue. It is the idea that those who share your beliefs are more charitable and giving. It is actually true that in our society, those who are religious are statistically more likely to give, and to give more, than those without any. It could be viewed as the inherent goodness of believers manifesting. Alternately, it could be viewed as an adherence to the belief system rather than something innate in the people who happen to be believers.
Community as pressure for charity: As it turns out, all it takes is one person who feels that charity is needed, and instructing those in their group to help out that can force them oblige. The beliefs can be used as leverage, but social pressure itself (whether it is from peers, authority figures, or both) can suffice.
Community as venue for charity inaccessible to those who are not part of it: Potentially related to the above is that charitable functions do not often arise outside of the kind of formal organizations that church happens to be. People may not often be exposed to charity benefits, or notices about them, outside of such institutions.
Cultural view of belief adding purpose: Also an inescapable and common viewpoint, as often brought up when discussing atheism in our culture as the point about religious faith being indicative of virtue. Many people hold this view, asserting not only that their religion gives them a feeling of purpose, that they could not even have a sense of purpose without religion. It seems to be a commonly accepted idea, whether or not it has merit.
Access to community granting interactions that feel like purpose: Interestingly, much of our happiness and our definition of self is contingent upon our relationships with other people. We define ourselves by profession, family role, and the method by which we interact with other people (with our own view of this method modified according to the generalized responses it provokes). And, this becomes a major part of our identity (or the entirety, for some people). Relationships with a religious community would be no exception. It would serve as a new group that you would interact with and a different set of people by which you can determine a social role for yourself. In that way, you can find a good amount of subjective purpose, even if you are unemployed, and have a sucky family and social life. When all else fails, you still have church, serving as a buffer against the failings of other pursuits in your interpersonal relationships which those who do not attend church obviously will not have.
Happiness granted by confidence in beliefs (and group polarization): Doubts are ugly little nagging things, aren't they? Confidence, even to the point of over-confidence and arrogance (or should I say: "especially to the point..."), leads itself to a strong sense of control over your environment, over your life, and to a sense of happiness that cannot be gained by those who are forever unsure. Now, one would expect religiosity to be correlated with confidence in religious convictions. And that is where things get messy. Because, if you get a group of people together with moderate opinions but who all agree with one another, eventually you are going to get people with stronger opinions, and more confidence than before. This is due to the ability that they have to confirm each others' perspectives and biases by merits of having similar ones and possibly due to introducing them to new reasons for why they might be acceptable. In this sense, church attendance could begin to correlate with religious conviction and intensity of faith over time, and it could itself lead to happiness, due to having their preconceptions confirmed once a week by almost everyone they see on a Sunday morning.
Changing views of church among the religious of different stripes: I alluded to this before. The role of organized, institutional religion is fluctuating currently, due to a decreased stress on the relevance of church attendance in regards to moral character and level of religious belief. Many of the devoutly religious leave their churches because it fails to meet their standards. Many of the loosely religious detest the institutions themselves, or the opinions of the people that they might meet there, and decline to go. Others are just too busy, don't care, or just can't find a church that suits their religious beliefs since, in the Information Age, you can convert more easily to religions that are not physically present in your area. The interesting part, as one could determine from previous mention of the negative influence that elevating church attendance has on the quality of the congregation, a downturn in amount of church-going Americans would probably be a good thing for the reputation of the churches. That is, under the circumstances that the infamous hypocrites and loonies all too often associated with them at this point actually wind up jumping ship at some point. Otherwise, it might be a truly complicated affair (if a significant decrease in church-goers occurs at all, that is).
Summary: It is far too difficult to determine whether religious ideology itself gives increased or decreased happiness, charitableness, or meaning due to how entangled religious belief is with religious organizations, with such a social institution having sufficient effects on the former three in of itself.
Wooooo. That was unnecessary. I should have just written the Summary and left it at that. Oh well...hindsight is 20/20.