Recent confrontations between the Vatican and the Sisters of Mercy, as well as with other groups of women religious, particularly with Americans, reveal a fundamentally different understanding of the relationship of Church and State, the sacred and the secular, held by the nuns, on the one hand, and the Vatican, on the other. Current Vatican policy assumes a rigid line between Church and State which makes any office-holding, either elected or appointed, in government, by either a priest or a nun, incompatible with the religious vocation. Although the first conflict between the Vatican and Sister Mansour of the Sisters of Mercy appeared to be primarily over differing interpretations of the relationship between personal morality and public policy in the specific case of payments for abortion, subsequent conflicts with the Sisters of Mercy over other nun office-holders went beyond specific differences over Church teachings on moral issues. The holding of any public office was defined as out of bounds for priests or religious: in other words, the Vatican pressed (and continues to press) for a very harsh interpretation of the restriction in the new Code of Canon Law (canon 285, 3) and for its world-wide observation.

A similar line has been taken in the case of the four priests who hold public office in the Nicaraguan revolutionary government and, most recently, the Italian priest who has been elected as a socialist to the European Parliament. In each case the resolution of the conflict is to force the person involved either to resign the public office or else be removed from their religious order (or, in the case of a diocesan priest, be suspended from priestly duties).