Historically, a primary function of the major religions has been social control. Sometimes this is explicitly recognized, as in Confucianism; sometimes it is thinly masked, as in Christianity. But, so far as I can see, social control has always been one of the main reasons for religion -- at least ever since the first priest-kings of ancient Sumer.
However, it is arguable that social control is a function of religion which detracts from and distorts its more spiritual functions. If so, then wouldn't secularism be of significant benefit to religious people who are more concerned with those spiritual functions than they are with controlling other people? At least, in so far as secularism might free up religions to focus on spirituality, rather than on controlling societies?
Please discuss.
I will point out an example in which what you're saying may very well have truth.
There was a time when the Pope was in charge of the entirety of Rome, and surrounding areas too called "the Papal States". When electing a Pope it wasn't just about appointing a spiritual leader, it was appointing a good political leader, one who could handle the temporal affairs as well as the spiritual affairs, even military affairs (see
Pope Julius II - Wikipedia, the free encyclopedia, who would lead armies into battle).
The problem with this was that sometimes, perhaps the spiritual qualities were overlooked, especially when the Papal states were in need of a good leader. The Catholic Church is known for vast amounts of corruption centuries ago and I personally think much of this can be brought down to the control of the Pope over large parts of Italy, where he was effectively a temporal King with spiritual authority over the rest of Christendom.
When the Pope renounced much of the Papal States and settled with today's Vatican City in the 1920s, there was a change of priorities when electing a Pope. The cardinals could really focus on the spiritual and theological side of things, the problems the Church as a whole was facing, not just the Papal States. (I'm not saying corruption was rampant in the Church until the 1920s, but I do think there was a shift in priorities).
With the Papacy content with Vatican city, we now had a Pope who didn't have to get bogged down with the affairs of his immediate surroundings and domain like an earthly king but could focus on taking care of his church across the world. I would say this shift led to a lot of change in the Catholic Church, notably in the form of the Second Vatican Council with its very forward-looking outlook (for that time) and even today with what we have in Pope Francis. (If the Catholic Church still held those swathes of land in Italy, I cannot imagine Francis being elected to take on those temporal and kingly roles.)
