Are we allowed to change our religion?
Answer: We have to distinguish between two aspects here.
1) Religious-political: Full religious freedom applies in free democratic states. Every citizen is allowed to freely choose their religion, to leave any religion as well as to change from one religious community to another. In many states with an Islamic majority freedom of religion, in this form, is not yet recognised or protected.
Art. 18 of the Universal Declaration of Human Rights (from 1948) states: Everyone has the right to freedom of thought, conscience and religion; this right includes freedom to change his religion or belief, and freedom, either alone or in community with others and in public or private, to manifest his religion or belief in teaching, practice, worship and observance.
2) From the perspective of Catholic faith: See our comments in Chapter 11, IV, and 4 Religious freedoms.