The Church is a "living active force doing great works," the Prime Minister said.
In his video message he added that he felt "proud to say this is a Christian country".
Easter is a "time to reflect on the part that Christianity plays in our national life", Mr Cameron stressed.
He said: "The Church is not just a collection of beautiful old buildings; it is a living, active force doing great works across our country.
"When people are homeless, the Church is there with hot meals and shelter. When people are addicted or in debt; when people are suffering, or grieving - the Church is there.
"Across Britain, Christians don't just talk about 'loving thy neighbour', they live it out ... in faith schools, in prisons, in community groups.
"And it's for all these reasons that we should feel proud to say: this is a Christian country.
"Yes, we are a nation that embraces, welcomes and accepts all faiths and none but we are still a Christian country."
The PM said he knew "from the most difficult times in my own life, that the kindness of the church can be a huge comfort".
It's thought to have been a reference to the support he received from the church after the death of his severely disabled son Ivan in 2009.
The Conservative leader also condemned the killing of hundreds of Christians by al-Shabab militants at Garissa University College in Kenya on Maundy Thursday.
"We have a duty to speak out about the persecution of Christians around the world too," he urged.
"It is truly shocking to know that in 2015, there are still Christians being threatened, tortured - even killed - because of their faith.
"In the coming months, we must continue to speak as one voice for freedom of belief.
"So this Easter, we should keep in our thoughts all those Christians facing persecution abroad and give thanks for all those Christians who are making a real difference here at home."