The church must not regard evangelism as secondary, Lyndon Bowring has told this year's Keswick Convention.
The CARE chairman was delivering the third lecture at this year's convention, being attended by thousands of Christians in the Lake District.
Bowring praised the church for its social outreach and encouraged Christians to get involved in serving their communities, but he also said the church needed to keep evangelism and social action in "creative tension".
While he expressed his support for social action and ministries to the poor, he said it was the church's priority to bring people to faith.
"We must not neglect evangelism and see it as secondary," he said. "The primary role of the church is to see people saved and converted. I really emphasise evangelism.
"There is nothing more important than seeing people saved. That doesn't mean we neglect the poor and fatherless. Please keep both these responsibilities in creative tension. Evangelism; yes, social action; yes. Don't pit them against each other, keep a healthy creative tension.
"Unless hearts are transformed, we're not going to transform communities. It's about heart transformation, first.
"That's our primary responsibility – declaring the message of the gospel… so they can be saved, transformed into a new creation."
Bowring pointed to the example of abolitionist William Wilberforce, who he said was just as passionate about saving souls as he was about ending the slave trade.
"You need to be converted if you have any hope of society being reformed," he said.
"But Wilberforce didn't live to see the fruit of his efforts. Evangelicals after him took up the baton, took up the call. By the end of the 19th century, the income from charitable giving in the UK was greater than the economies of Denmark and Portugal, and 75% of all charities were evangelical in UK in 1895."
Bowring spoke of the need for Christian engagement in the world today, particularly the areas of abortion, hunger, and attempts to legalise euthanasia and assisted suicide.
Speaking on the same day as the Court of Appeal in London rejected a right-to-die challenge by the family of the late locked-in sufferer Tony Nicklinson, Bowring said CARE would "fight that to the end".
"Once you speak of rights to die, people will feel it a duty to die," he said.
He went on to encourage people to "step out in faith" in serving and demonstrating the love of Christ to their communities.
"I will encourage you to ask God what, if anything, more can you do in your community?" he said.
"You may have to lay something down to do something new. Say, 'Lord, show me, is there something more I can do than I have been doing? We're all in danger of being self-centred."
He added: "I'm encouraged overall with what I see the church doing in terms of evangelism and social action. Overall, encouraged, that people are trying to proclaim and demonstrate."