Suppose that you take it as an axiom that substantial portions of both the Christian religion and the Islamic religion are profoundly negative forces in the world that greatly detract from the well being of humanity.
Suppose that you further acknowledge that a tendency to be religious is a natural personality trait. Some people may have it to a greater degree, and some to a lesser degree, but this tendency is inherently a part of human nature for a great many people, in some people to a great degree.
Thus, it may be impossible to have a human world that is truly secular.
Contrawise, it may also be impossible to have a human world that is full of truly devote people. The Hebrew Bible is to a great extent a chronicle of Pyrrhic efforts to accomplish this that failed over and over and over again despite the best efforts of its rulers, priests and prophets.
Of course, even if a tendency to be religious is part of human nature, the way that this tendency manifests and plays out is almost purely cultural. No one is born Christian or Muslim or Buddhist. Someone with a natural tendency to be religious will manifest that in the shape of whatever religious beliefs they are exposed to in their lives. And, even during someone's life, a person's religious worldview through which that person expresses their tendency to be religious can change.
It is not self-evident what must be part of a belief system for it to feed into and satisfy the tendency of some people to be religious. Must it be metaphysical? Must it be unknowable? Must it involve a metaphysical realm that acts with moral purpose in our world? Must it involve an afterlife? Must it provide a way to deal with grief and injustice in the world? Must it merely provide a moral code? Are rituals and life scripts the key elements of what naturally religious people need?
At any rate, if the human world cannot be truly secular because Nature abhors a religious vacuum, then the alternative to the harm caused by the religions that we do have, would be to devise one or more new religions that are less harmful and find a way to get people to convert en mass to them.
This is not unprecedented. Mass religious conversions of whole populations that virtually wipe out the religions that came before them a living faiths have been documented many times within the span of the historically attested past. It hasn't happened particularly frequently, but it has definitely happened.
Conventional wisdom is that this has been driven by sincere true believers in an organic fashion. But, if one really understands the process, and there is not actually any metaphysical world out there, so that no religion can actually be true, shouldn't it be possible to intentionally create a religion for this very purpose? Issac Asmiov's Foundation series poses just such a scenario.
If one could do it, and the status quo is as bad as is assumed axiomatically for the purposes of this post, isn't this not just possible, but morally obligatory to do so?