Professor John Lennox today called on Christians to speak out about their faith in the face of militant atheism and a secular culture.

Speaking at this year's Evangelists' Conference at All Soul's Langham Place in London, Lennox also answered some of the common objections to the Christian faith.

Prof Lennox read from 1 Peter 3:14-15, and pointed out that before verse 15, which says to be ready to explain your Christian hope, is an encouragement not to be afraid.

"There is enormous pressure to privatise the Christian faith," said Lennox. "[Our culture says]: 'You believe in God? Fine, but be quiet about it.' But I want to encourage you to not be silent. So, we have fear to combat.

"The New Atheist onslaught is beginning to wane... but Dawkins et al are still wreaking havoc in the minds of young people," he added.

The professor of mathematics regularly debates well known atheists such as Richard Dawkins, and has written books challenging the atheistic conclusions of scientists such as Stephen Hawking.

Lennox had just returned from an international tour. "The interest in this topic in Australia is unbelievable," he said. "I went to five cities asking... 'Do science and God mix?' It was sold out and packed weeks in advance. Australia is a very secular society, but there is enormous interest in this kind of thing.

"I am overwhelmed by the number of people who come to faith at these events. I get letters from people who were moved."

He pointed out a series of logical inconsistencies in New Atheist work, such as the claim from Lawrence Krauss: "Because something is physical, nothing must be physical – especially if you define it as the absence of something."

Lennox added that many atheists do not support the ideas of militant atheists such as Dawkins, Krauss and others. "I have many atheist friends who thank me for taking Dawkins on," he said.

Turning to the first letter of Peter, Lennox said that the apostle envisages a dialogue, and we do not need to wait for a question about our faith to start a conversation.

"He is encouraging us to get involved in a dialogue. One of the things we are required to do is to stimulate dialogue... Try this next time you meet someone new – keep asking them questions until they ask you one."