Apparently a person affected by religion has a certain disadvantage, since he is busy doing useless things and limited in his capacity for analytic thinking. This might therefore be a helpful advantage for people not suffering from this kind of mental disorder.
And indeed many governments use religion to solidify and justify their power and keeping their subordinates ignorant and harmless for them. Therefore religion has often been made it into a very efficient tool of politics and for personal ambitions of ruthless rulers.
However, as it was explained before, religion is not an invention of politicians but is an independent entity with its own selfish intereswt in reproduction. If it is used by governments for their own purpose, it is in the same way as computer viruses are used to distribute hacking tools or advertisement or as DNA viruses are used as biological weapons in war. It is not the cause of their existence but merely a sort of domestication in order to turn them into useful tools. Many politicians who use religionn as an instrument of power are often not free of the virus themselves and are to a certain extent affected by the religion, which they use as a tool, too.
Independent from this phenomenon the questioin remains: If somebody is free from religious superstition and has understood its nature and mechanism, should he be interested in keeping religion alive so that he can gain a personal advantage over those people who are unaware of the virus and suffer from all negative consequences of religion? Or shoukld he be interested to help others to free themselves from religion and eliminate it from society?
Many of those who like to use religion as a tool to keep others ignorant, who use it as some kind of opium of the people and who don't practice religion in their own private lives, since they know better, underestimate thge influence that society has on the life of every single individual human being.
Their private lives in their own houses cannot be completely independent from what is going on in the ouitside world. In fact they depent on the society in every aspect of life. A religion that suppresses technological advancement will paralize society and even those who are free from religion will not be able to enjoy these technological advancements in their private lives, since they were never invented.
If religion limits personal freedom and puts restrictions on things that may be enjoed or consumed, these things will not be available for those who don't follow this religion in their homes. They simply won't have access to these restricted things in their private lives either. Or at least the access to these things will always be severely limited and made far more difficult. Furthermoire there is the danger that the violation of the religious rules in their private sphere may become disclosed and the society imposes a punishment on them.
So whatever personal advantage they may gain by keeping others religious and being free from it themselves it is more than out-weighted by the disadvantages it has on their own lives.
In many aspects technology has allowed even lower class members of modern society to havea better and more comfortable life than the ruling class in former centuries. Even welfare recipients receive medical assistance and can live in climatized rooms, while not even the monarch of the Middle Ages could enjoy such kind of luxury.
Therefore it would be no good idea to promote religion in order to keep others ignorant while being free from it in our own private life. The negative effect that religion has on the whole society will backfire on us, since we depend on the society we live in and our private life cannot be totally separate from society.
It is therefore necessary to reduce the influence that religion has on society. Using religion as a tool is short-sighted. At the end it will work against those who think they control it. Religion cannot be totally controlled, since it is an autonomous entity with its own selfish interests, which are the reproduction of itself and the optimization of the mechanisms of its own reproduction.
Religion is pathogenous, malignous and highly virulent. It should not be played around with.