From Wikipedia:
After the 1979 Iranian Revolution, Christianity in Iran is recognized as a “protected religious minority” and according to the Constitution of Iran have the freedom of religion and even have a Member of Parliament (MP) representing them.
However, evangelism and missionary work and converting Muslims to Christianity is prohibited by law, and Christians in practice may also face some discrimination as well in their lives.
In the Islamic Republic of Iran, there is officially no crime known as apostasy in the penal code (although there was a law about it prior to 1994). The last known execution for this crime was in 1990. However, despite there being no official civil law of apostasy, judges may still convict a defendant of that crime if they rule based on religious fatwas. As a result, a few people had been convicted of it, but there were no known executions.
In 2011 a man was executed in Ahvaz, Iran for blasphemy and “speading corruption on the earth” (Mofsed-Fel-Arz) when he claimed that he was God, and attracting a “following” around himself. According to the fatwas, for a man, if convicted, the punishment would be death by hanging, for a woman, it would be life imprisonment. The apostate would be given three chances to repent and convert back to Islam.
Barack Obama’s September 30, 2011 statement read:
“The United States condemns the conviction of Pastor Youcef Nadarkhani. Pastor Nadarkhani has done nothing more than maintain his devout faith, which is a universal right for all people. That the Iranian authorities would try to force him to renounce that faith violates the religious values they claim to defend, crosses all bounds of decency, and breaches Iran’s own international obligations.”
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Here is Iran’s response:
Gholamali Rezvani, the Gilan Provincial Political/Security Deputy Governor, stated:
“Youcef Nadarkhani has security crimes and he had set up a house of corruption. ... Nobody is executed in our regime for choosing a religion, but he is a Zionist who has security crimes.”