Evangelii Nuntiandi
56. The second sphere is that of those who do not practice. Today there is a very large number of baptized people who for the most part have not formally renounced their Baptism but who are entirely indifferent to it and not living in accordance with it. The phenomenon of the non practicing is a very ancient one in the history of Christianity; it is the result of a natural weakness, a profound inconsistency which we unfortunately bear deep within us. Today however it shows certain new characteristics. It is often the result of the uprooting typical of our time. It also springs from the fact that Christians live in close proximity with non-believers and constantly experience the effects of unbelief. Furthermore, the non-practicing Christians of today, more so than those of previous periods, seek to explain and justify their position in the name of an interior religion, of personal independence or authenticity.
Thus we have atheists and unbelievers on the one side and those who do not practice on the other, and both groups put up a considerable resistance to evangelization. The resistance of the former takes the form of a certain refusal and an inability to grasp the new order of things, the new meaning of the world, of life and of history; such is not possible if one does not start from a divine absolute. The resistance of the second group takes the form of inertia and the slightly hostile attitude of the person who feels that he is one of the family, who claims to know it all and to have tried it all and who no longer believes it.
Atheistic secularism and the absence of religious practice are found among adults and among the young, among the leaders of society and among the ordinary people, at all levels of education, and in both the old Churches and the young ones. The Church's evangelizing action cannot ignore these two worlds, nor must it come to a standstill when faced with them; it must constantly seek the proper means and language for presenting, or representing, to them God's revelation and faith in Jesus Christ.
Source: Evangelii Nuntiandi (Vatican.va) · © Libreria Editrice Vaticana