From here, relative to his visit to France:
It seems obvious to me today that laïcité (the French policy of exclusion of any religious content in the life of the state) in itself is not in contradiction with the faith. I would even say that it is a fruit of the faith because the Christian faith was, from the start, a universal religion, therefore not identifiable with a State and present in all States. For Christians, it has always been clear that religion and faith were not political, but another sphere of the human life…politics, the State, were not a religion but a secular reality with a specific mission… and both must be open one with regard to the other. In this direction, I would say today, for the French, and not only for the French but for the rest of us, Christians of today in this secularized world, it is important to live with joy the freedom of our faith, living the beauty of the faith and making it visible in the world of today. It is beautiful to be a believer, it is beautiful to know God, God with an human face as Jesus Christ… to show the possibility of belief today. Beyond that, it is necessary for today’s society that there are men who know God and can thus live according to the great values that he has given us and to contribute to the presence of values which are fundamental for the building and survival of our States and our societies.
France has a much longer and more deeply rooted tradition of secularism than we do in the U.S., and there are many lessons to be learned from that.
It is also instructive to compare this statement with that of the French historian Ferdinand Lot:
In spite of its efforts, the (Catholic) Church will not come to dominate the State. The basic reason, as we have seen, is that the Christian Church was not set up for the life of this world. It did not bring to society any new social or judicial concept. She accepted without resistance (or real repugnance) the institutions of the Roman State. She could keep its management and continue its life. This was even more the case with the barbarian states, of which Christianisation was superficial.
The medaeval and modern State, heir in part of the Roman State, could not be absorbed by the Church. Bathed completely in Christianity, it kept its identity from becoming a part of the Church. If the roots of the State had not been not profoundly grounded in the Roman past, the medaeval State would have been dissolved in the Church and the Church in the State, and one cannot see how the modern concept of the separation of religious conscience and the State could have developed, let alone be born.
And there is the secret of the basic difference, more basic than one might believe, between Christian and Islamic states. Islam carries not only a religion but a system of justice, a political system, of which one searches in vain for an equivalent in the Gospel. Thus this way of speaking is inexact: with rights, customs, even methods, none of this can be discerned from religion. It is impossible to touch what it is without running into, without risking offence, of dogma. And since rights, customs, and methods are rudimentary in a little-evolved society, it is a superhuman task to adapt an Islamic society to modern life. Here the religion will not allow itself to be reduced to a part that fits. It is in vain to find a place for it, because its place is everything or nothing.
(Ferdinand Lot, La fin du monde antique and the début du moyen âge (The end of the ancient world and the beginning of the middle ages) Paris: Éditions Albin Michel, 1968, p.64 (originally published 1926)