Belgium is the one of the most secularized country in the Western Europe, together with France and the Netherlands. Belgium never underwent a process similar to that of France, where in 1905 a law introduced separation between State and Church. Therefore, State and Church relationships in Belgium are still organized along the constitutional principles adopted in 1831.
Those principles establish freedom of religion and guarantee the right to free and public practice (article 19); they also protect the right not to profess any religion (article 20).
According to the first Belgian census in 1846, 99.8 percent of Belgians declared themselves to be Catholic. In the first decades of Belgian existence, the Catholic Church controlled education, culture, and charity. In the second part of the nineteenth century the radical Liberal faction and, later on, the Socialists challenged the power of the Church by separating these functions bit by bit from the Church.
By the 1980s Catholic Church also decreased their effects on social issues and the society. Then Cristian Party (they preferred to be called Christian instead of Catholic, which was a way of distancing themselves from the Catholic Church) established to represent the religious perspective on the state actions.
Young adults have always lived in a world conceived to be controllable and calculable: the economic, the educational, the domestic, and the procreative world. Consequently, God is more and more removed from the world of the young. Many can no longer believe in God because “they have the world in their hands.” Middle-aged and older men and working women have also become progressively caught up in such a world. Only middle-aged and older housewives have been sheltered from such a world and have, rather, known a world based on value such as tradition and devotion, and on personal, total, lasting, and natural relationships. This explains why generational experiences and employment are the only social variables which bring about significant variations in beliefs, ethical attitudes, and ritual behavior.
Nonetheless, nearly 80 percent of Belgians still call themselves Catholic. This is certainly to a great extent also a consequence of the presence in Belgium of omnipresent Christian organization.
Based on the survey, roughly 86 percent of the respondents participating in this survey said they know something or a great deal about Christianity. 
On the other hand Although there are several reasons for this, two important events in particular have led to these discussions. First, there are the scandals of sexual abuse and the way the Catholic Church did (not) handle it. Second, the increase of religiously inspired terrorism and religious fundamentalism make many people criticize religion (in particular Islam) and fail to see any social benefit in religion (any longer)
Catholic Religion in Care Services
& Voyé, L. (1990). From pillar to postmodernity: The changing situation of
religion in Belgium. SA. Sociological Analysis, S1-S13.
 Dobbelaere, K., & Voyé, L. (1990). From pillar to postmodernity: The changing situation of religion in Belgium. SA. Sociological Analysis, p1.
 Dobbelaere, Voye (1990), p2
 Dobbelaere, Voye (1990), p5
 Franken, L. (2017). State Support for Religion in Belgium: A Critical Evaluation. Journal of Church and State, 59(1), 59-80.