Is it morally justifiable for individuals to continue practicing a religion solely for the psychological comfort it provides, while turning a blind eye to the potential dangers of the religion's power dynamics and its potential to oppress others? How can one balance personal beliefs and benefits with the societal harm caused by religious institutions?
Research has linked 'religiousity' to a number of personal benefits, eg reduced depression Is there a relationship between spirituality/religiosity and resilience, reduced risk of heart-disease and cancer (!) Association of Religious Service Attendance With Mortality Among Women, and to resist or recover from addiction Religious Faith and Spirituality May Help People Recover from Substance Abuse + many more papers. There's also research suggesting the impacts of loneliness are comparable to obesity, & religious participation can help with the former. And religiosity even correlates with a longer lifespan, by an average of about 4 years.
There are clear social risks though. Extremism, like Puritans or the Wahabi Islamic sect. Religious conflicts, like the three centuries of the European Religious Wars, or Sunni-Shia conflicts like embodied in the Saudi-Iran conflicts, or the ethno-religious Tamil-Buddhist Sri Lankan conflict. Resistence to social change, like the biblical prohibition against usury which by ceasing to be enforced in Christendom probably significantly helped to end Feudalism, or gender decrees that reduce opportunities for skilled workers and bright minds to define themselves, or scriptural passages were used to justify slavery in Christianity and Islam.
So, I'd say your question holds clear merit. There are well evidenced personal benefits. And much discussed social negatives. We can of course find converse cases, religiosity has been linked to unwillingness to seek mental health support, and Abolitionists were were primarily motivated by religious ideas as were the first vegetarians who wanted to reduce animal suffering. But I'd say the balance is clear.
Religions in order to persist, must tend towards being conservative, and resistent to change, and that seems to relate to a lot of the problems they generate. I think it's very interesting to look at the precise mechanisms for reform, in different religions - this seems an often neglected topic. In Islam, the Koran is the revealed word but distinct schools of jurisprudence have arisen, with associated sects, it makes secular governance difficult to achieve in Islam because Mohammed was explicitly a political as well as military leader and gave political decrees for his times. Christianity has been crucially shaped by it's Ecumenical Councils, the East West split ended Hesychasm, and the rise of Protestantism led to doctrinal fragmentation that has allowed for instance Prosperity Gospel churches to gain large followings while having been declared formally heretical by most other Christian groups. In Judaism they have the Beth Din Rabbinical courts, and the tradition of the Talmud continued there is of detailed exegesis by argumentation, this has proved remarkably capable of both updating and keeping the spirit of religious decrees, like how interpretation of Eruv has maintained Jewish areas, ethno-religious nationalism is creating big issues in Israel but then it also did since at least Roman times - the Nevuah or time of prophets is considered to have ended, they could alter the 'core code'. In Buddhism the Sangha makes decisions about monastic life and exegesis, in Therevada the canonical texts are all considered to be from the time of the Buddha, while Mahayana allows further teachings to be canonical which has allowed it more doctrinal flexibility, but also war-priests and non-celibate monks in Japan. In Sikhism, they allowed 10 gurus over two and a half centuries, then ended that phase with a codified text considered to be the 'final guru', in many ways they picked good bits from monotheism and polytheism, and have a remarkable and interesting practice that includes one of the best charity practices of any major religion, and their ideas should be better known. Hinduism is more culture than religion, with a sprawling array of gurus and mela gatherings where they come to the fore, which has seen hugely dynamic 'religious entrepreneurialism', but also the wiping out of Buddhism in the mainland despite a Buddhist king being first to unify India, and a current surge in ethno-nationalism, Hindu thought has tended to react to react to new faiths then integrate the reaction eg Shankaracharya to Buddhist thought.
When choosing an established major faith, but disagreeing with it on some major point, the degree it is capable of changing must I'd say be an issue. Major religions all have modern sects, branches or interpretations that have arisen to address conflicts or meet culturally varying needs, so it's generally possible to pick and choose tenets, though this may limit how many adherents there are locally, and so the social benefits of practicing. Human institutions are intrinsically problematic, especially when shielded from criticism or accountability. So I'd say there has to be a balance struck, between continuity and capacity to change - we cannot live in the past, without killing the future.
The more interesting idea to me, is can we gain the benefits religions have provided, without the negatives? I really like the idea that religions can be considered as assemblances of 'metis', of practical crafts, of how to live well together: Whence Comes Nihilism The Uncanniest of all Guests?'. Durkheim was arguably the first thinker to really successfully grapple with how religion has been done differently outside of the Abrahamic faith's sphere, and his points about anomie vs social cohesion from enactment of shared attitudes towards sacred values, can help us understand that habeus corpus (no detention without trial), or values of scientists that bind together their international community, can be related to the mechanisms of religion. There's a lot of overlap I think with Nietzsche, who can be understood better in my opinion by recognising how there is a tension in religious discourse between what we keep and what can be changed, that he wanted a recapitulation of the epoch of (largely) preliterate religious fluidity.
Sapolsky has a great lecture on the possible Biological Underpinnings of Religiousity. The TLDR is, maybe mild schizophrenia has related to hearing intuitions about social needs as commandments, and OCD could relate to rituals that have helped bind together groups doing them. China under communism undertook one of the most thorough purges of organised religion, and yet now is among the most superstitious countries in the world, with big focuses on the power of certain numbers, and 'energy directing' practices that used to exist in pretty much all cultures but have elsewhere largely been consigned to history.
I would make the case Ancient Rome and China by being extremely militarily unified, were able to be very religiously cosmopolitan and diverse. Whereas, the fragmented Holy Roman Empire, or warring Islamic empires with major ethnic divides, tended to use limits on 'religious entrepreneurialism', ie dissent about interpreting religion, to try and limit political fragmentation. So, I would point first of all to the idea securing peace, can help foster space for religious dynamism.
We accrue cultural 'metis' given relatively stable times, and the dynamism of the last century seems to have obscured this. We have major social problems, like suicide being the leading cause of death for ages 16-45, loneliness being a huge problem, and a 'meaning crisis' characterised in various ways. People will innovate ideas towards dealing with these, and in time they will form a cultural body, and future people may call that a religion. But at root there is just an art of how to live better together, and we should all try to learn it, and contribute to that new, and ever-dynamic 'book'.
Reduce the statement to neutral language and evaluate it, then evaluate the inexplicit premises to see if the evaluation of the neutral language statement is relevant to the specific topic.
Is it moral to participate in an activity which causes net harm to others but provides net benefit to the participants, supposing that one believes that about the activity?
Are some religions such an activity, relative to whatever things would be like without them? What do I know and why do I think I know it?
Are there alternatives, what do they seem to have been historically and in the present day, and are they any better?
If so, do any / many religious people actually believe that their religion causes net harm to others relative to the alternative?
If so, is the net marginal harm per additional religious practitioner positive or negative?
If so, which religions, why, where, and to what extent?
Certainly one ought not to "turn a blind eye" to injustices committed by institutions in society--whether he belongs to them or independent of them. It is fair to say that--based on the universal Moral Code--it would be morally wrong to knowingly support them, just because he derives some psychological benefit(s).
However, one must be careful to not commit the Fallacy of Logic (Over-generalization) by assuming that all religious institutions are prone to (or guilty of) committing social harm. Nor believe that there are not those within erring institutions who are assiduously seeking reformation. The "personal benefits" do not relieve anyone from maintaining vigilance against harmful conduct within any institution, religious or not.
Further, it should be cautioned that, while there may be several psychological benefits for being religious, there are other more important reasons for membership. Most parishioners would find solace in theological benefits for their belonging.
Of course it's not morally justifiable to avoid moral problems through religion. There was a commandment to give back on a regular basis in Abrahamic religions and there is good, sound, verified purpose to this.
This is not at all an excuse to escape culpability in one's acts. Unfortunately, religions such as christianity have normalized the idea of "no fault" in ethical decisions if you follow Jesus ("All of your sins will be forgiven."). It is completely reprehensible and an act of heresy.
People who use religions to find comfort are avoiding their world.