Is implementing the Social Reign of Christ the King equivalent to what the Muslims do in their own countries with Sharia law except that the Reign of Christ is the Catholic religion instead of Islam?
Were the Catholic states of the past that did so equivalent to the Muslim states under Sharia law?
A good example of the difference is that a Catholic state would allow children to marry who they wish, whereas in a Muslim state they would have to have their parents approval.
There are many other differences, for example, pertaining to divorce and remarriage, abortion, contraception.
In a Catholic state the laws would be stricter.