It is not a requirement to agree with any particular political decision or religious ideology to visit Iran.
While in Iran, you will hear a lot of different views from different people about politics and religion, and inevitable all travellers will have their own thoughts.
However, the Iranian government is very sensitive to any foreign involvement in internal political affairs, so any political activity inside Iran, particularly directed against the Iranian government, could lead to arrest.
At least while in Iran, it is best to keep your views private on political and religious matters.
