The literal insanity of mainstream public discourse, and the lack of insight of this fact, suggests that Man without religion is non-viable.
To put matters another way - religion is the most important thing in the human world.
Of course, a few individuals, in the short term, can survive atheism mentally intact; but there is no evidence at all that this is a possibility for human societies over more than a few decades - then the signs of insanity (incoherence, exitinction) become more-and-more obvious... or they would do so if loss of insight was not itself a prime sign of insanity.
So insanity shields us from knowledge of our own insanity, because insanity destroys insight as much as it destroys judgement - it affects the whole mode of thinking.
How, then, do we know we, as a society, are insane?
1. By applying older judgements, from the time before Men became insane - reading old books, talking to non-modern people...
2. By looking at the basic biological viability of atheist societies in terms of reproduction, demographics, response to direct and immediate threats, scale of priorities ... Compare societies and groups that are biologically viable, with the modern atheist societies that are not...
3. By reflecting on how we feel about Life. Insane people are almost always miserable - dysphoric, despairing, desperate... almost all of the time. Even the euphoric frenzy of mania is brittle, and crashes into suicidal self-destruction with a high frequency. Is there hope?
In conclusion - religion is the most important thing.
Religion is necessary for long term motivation, for social coherence, for purpose, and to enable the individual to be a part of the whole.
Since religion is necessary, if or when humans either dispense with religion or else place it anything lower than first in priority; then they as individuals and their societies will begin to fall apart and spiral towards alienation, purposelessness, inability to perceive or reason what is important, cowardice (i.e. short-term selfishness), desperation and all the rest of it.
Modernity is the experiment of Man living without Religion. The experiment has been running for several generations.
But the experiment of modernity has deprived modern people of the motivation, honesty and ability to evaluate the results of the experiment - by the always changing criteria of modernity, modernity sees no alternative to itself...
Conclusion: Religion is objectively necessary; and, by one kind of reasoning, therefore true. If you are not religious you are living in error. If you are not religious then you need to become religious. The question you must settle is not whether you should be religious, but which religion you will adopt.