Two weeks ago I encouraged you to email the Iranian President directly. Even more powerful, however, is the Supreme Leader of Iran, Ali Khamenei. Today please email him directly at firstname.lastname@example.org and simply request that Iran's government release Pastor Abedini.
You may want to quote the United Nation's Universal Declaration of Human Rights, which states in Article 18:
"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."