In the paper it is argued that the author of “Description of Customs…”, who was a Catholic priest, showed greater tolerance for non-Christian religions than for Lutheran and Calvinist denominations. This was linked with the fact that Protestants effectively competed with Catholic nobility in the same spheres of public life to gain social and material goods in Poland in the times of the Saxon Dynasty. Kitowicz exhibited an intense dislike for deists as he accused them of a lack of religiousness in its essential aspects involving the cultivation of sacred rituals and ceremonies, and he claimed they were sufficiently satisfied with pure ideology. Generally speaking, the author of “Description of Customs…” did not attack other religions for reasons related to faith; he did it for pragmatic reasons, paying attention to social interests of Catholic nobility, or in connection with morality, in the case of atheists and nonbelievers.