From Le Regard Politique, my translation. (The English version of the work is Seeing Things Politically.)
[Leo] Strauss shows that at any rate some people can free themselves entirely from social pressure in order to conduct themselves freely, by being capable at the same time of understanding their own interests and the prejudices of society, and yet also conveying to the careful reader of the text their real meaning which is a long way from the prejudices of that society. In that sense, Strauss is indeed a great liberator.
Strauss thus helped me to...reconsider european history. The theories of secularisation appeared to me more and more like sociological fairy tales based...on the premise that there were ages of faith when people were necessarily religious...Theories of secularisation subject the human spirit to necessity -and it's also by necessity that the human spirit frees itself from the necessity of religion. Let me put this as simply as possible: if there were many atheists in the ages of faith, and if there remain some believers in the age of secularisation, then we need to reconsider all our theological and political history.
Put roughly, Strauss argues that philosophers concealed their atheistic tendencies in societies dominated by religion by writing texts which could, on the surface, be read in accordance with orthodox religion, but to careful readers would reveal their intended, esoteric meaning.
Manent uses this claim to emphasise the real possibility of free thought in societies such as ours where there is overwhelming social pressure to conform to an orthodoxy of secularity. The human spirit remains free to find and articulate philosophical and religious truth whatever social pressures are put on it. Instead of a view of history driven by sociological necessity and divided neatly into periods of faith and periods of secularisation, we should instead look for a far more complicated spiritual history where the freedom of spiritual search is concealed but nonetheless exists.
Two common themes, I think, from Manent here. First, the importance of human free agency (particularly in politics) in deciding how we live, as opposed to postulating deterministic sociological laws. Secondly, the dismissal of seeing our age as specially modern, rather than being simply subject to the same perennial human questions (here, of religious belief).