The Labour Leader made the comments on a visit to Praise House, a black majority church in Croydon on Sunday, where Mr Miliband also said he wanted to reduce the number of people who are reliant on foodbanks by tackling people's personal debt and expanding credit unions, in a possible tie-up with the Church of England.
Ed Miliband also called on the EU to restart a full search and rescue mission in the Mediterranean Sea, after hundreds of African migrants drowned on over the weekend fleeing conflict in Libya on a crowded boat. The latest incident follows several similar tragedies over the past few months.
On Thursday Italian police said Muslims who were among migrants trying to get from Libya to Italy threw 12 fellow passengers overboard, killing them, because the 12 were Christians.
Speaking to Premier before Sunday's church service, Mr Miliband, an atheist, said: "We're going to have an envoy for religious freedom, reporting to the Foreign Secretary while we will have a council in the Foreign Office, thinking about how we deal with these issues.
"And I think it's really really important that Britain takes a lead on these questions and we speak up about this, we speak up about the persecution of Christians around the world."
The EU ended its maritime rescue operation, Mare Nostrum; last year after some EU members said they could not afford it and expressed concerns that it was encouraging more migrants. The EU now runs a more limited border control operation called Triton.
Meanwhile, a new video released by Islamic State shows at least 30 Ethiopian Christians being executed in Libya.
While it's not clear how many Christians were killed, Reuters is reporting that at least 30 men in two groups were beheaded or shot.
The men are referred to in a subtitle as "worshippers of the cross belonging to the hostile Ethiopian church".
Speaking on the domestic issue of foodbanks, which usage figures out this week are expected to show have surpassed one million people, Ed Miliband said he would be open to working with the church on cutting the number of people who used the service by improving the minimum wage and expanding credit unions.
"I'd be very very happy to look at ways in which we can support the credit union of the church. Credit unions are there for one purpose and one purpose alone which is to give people affordable credit. Payday lenders are there for one purpose to make profit out of people.
"I think credit unions have a really important role so I think we have got to sort out these things and it would be an objective of my government to reduce the number of people on foodbanks."
Ed Miliband speaking to Premier's Desmond Busteed:
