There are approximately 250.000 Christian Iranians. Iranian Jews build the biggest jewish community outside of Israel in the middle east.
Despite foreign policy problems of Iran and Israel or the west in the last 30 years, these communities are living in Iran for more than 1000 years. Contrary to Europe where Jews where persecuted in large parts of Europe (not just Germany) during the crusuades and later, Jews could live peacefully in Iran.
The persian emperor Cyrus the Great freed the Jews from babylonian imprisonment and returned them to the promised land with the commission to rebuild the temple. Cyrus the Great is mentioned as Messiah, a divinely appointed leader, in the Bible and the Torah. The greek historian and philosopher Xenophon wrote his master piece Cyropedia about the way Cyrus the Great ruled his empire. Benjamin Franklin had a copy of Cyropedia and was strongly influenced by it.
Cyrus the Great also proclaimed what has been identified by scholars and archaeologists[who?] to be the oldest known declaration of human rights, which was transcribed onto the Cyrus Cylinder sometime between 539 and 530 BC.
Cyrus the Great had the strong belief that in his empire everyone should be able to follow her/his own religion.
Since ancient times, Iranians have been tolerant to especially Jewish and Christian communities. Hence even iranian jews that are now living in Israel since the beginning of the state Israel still feel as Iranians and are often loyal to Iran, not the islamic republic.
Contrary to Saudi Arabia where you can not find a single synagogue or church, there are more than ten churchs and synagogues just in Tehran. Iranian Jews and Christians can freely excersize their religion in Iran.
Head to http://theotheriran.wordpress.com/tag/minorities/ to read more about this. The government of Iran is intolerant, and thus persecutes convertites, but the iranian people are open to other religions. In fact a lot of muslim Iranians are for example happy to enjoy Christmas celebrations.
Iran is of course still a clerical dictatorship, so no one is free. Also the shiite majority of Iran is not free. But you can evaluate religious freedom by checking what people of different religions can do in Iran. Christian and Jewish iranians are free to study, work, gather together in churches or synagogues and exercise their beliefs. They have also representatives in the parlament, but otherwise they have often no access to posts in the government, but these posts are also not accessible by most shiite iranians except they have specific bondage with the ruling parties.
Just compare the situation with the situation in the other middle eastern powerhouse Saudi Arabia, where every non-sunni is considered as a second class citizen, where no one can build a church or a synagogue and where even shiite muslims have almost no rights and are subject of harsh repression.
Thanks to Iran’s rich and tolerant history the situation is way different in Iran.