As part of the agreement the country will get rid of 98% of its stockpile of enriched uranium. In turn sanctions imposed by the United States, European Union and United Nations will be lifted allowing Iran to return to the global oil market.
Iranian president Hassan Rouhani said the deal marked "a new chapter" in relations with the world and the Islamic republic.
Speaking in Tehran, Mr Rouhani said: "The sanctions regime was never successful, but at the same time it had affected people's lives."
President Obama gave an address moments after the deal was made. Addressing critics he said: "This deal is not built on trust. It is built on verification."
Revd Lazarus Yeghnazar, President of 222 Ministries said: "Once again Iran and its leadership has been given a unique opportunity.
"Many are apprehensive both Iranians and non for its past track record over three decades.
"I'm praying and hoping they will seize this opportunity....to do something accountably and respectively both for the Iranian citizens and the international community.
"In a pragmatic sense I exercise a cautious optimism and in a spiritual sense I prayerfully look forward, praying for all the leaders in the country.
"All of the Christian leaders around the world are praying for this, that God will soften their hearts...that the Government will have bigger issues to pursue and leave the Christian community alone to worship their God as they want."
Announcing the deal, Federica Mogherini, the European Union's foreign policy chief, appearing on stage in Vienna alongside Iranian foreign minister Mohammad Javad Zarif, said: "Today is an historic day.
"We are creating the conditions for building trust. No-one ever thought it would be easy...Despite twists and turns in the talks, hope and determination enabled us to overcome all the difficult moments."
The deal's been labelled a 'bad mistake' by the Israeli Government. Prime Minister Benjamin Netanyahu said it would lead to Iran getting a "cash bonanza" which will enable it to "continue to purse aggression and terror in the region and the world".
Listen to Revd Lazarus Yeghnazar speaking to Premier's Antony Bushfield: