Most Christians feel confident about sharing their faith - but with some people more than others, according to research by London City Mission (LCM).
People were most likely to share the Gospel with friends and family (42% each), followed by non-Christian work colleagues (37%).
They were less likely to share the Gospel with people from a different social background (30%) or marginalised groups like homeless people or asylum seekers (20%).
However the study found that most Christians feel confident to share their faith with people who are not Christian (74%), and an even greater number recognise the importance of this (89%).
Over three quarters (76%) said they would like to talk more often about their faith with people who aren't Christians.
The findings have prompted LCM to warn that some social groups may be missing out on the Gospel, while encouraging Christians to get "outside of their comfort zone" and engage with people they might not normally.
It has created a new resource hub and podcast called Everyday Evangelism to help them do that.
Efrem Buckle, Deputy CEO and Director of Training at London City Mission, said, "We know that half of all Londoners live in gospel poverty which means they don't know a Christian who can share their faith with them. We also know that those Londoners who live in gospel poverty are also likely to be part of our most deprived communities.
"It's down to us to act and start to build bridges to share the gospel with people on our doorsteps. I see opportunity in these numbers – an opportunity to reach someone we haven't met yet with the life-changing message of Jesus' love."
"This may be outside of our comfort zone, but my advice is to start with one person. There may be someone you see as part of your everyday life that you can open a conversation with.
"I've got to know the delivery driver who I've been able to share my faith with. I recognise that they're a person to be seen and valued of care, not just to meet my convenience. Let God keep our eyes open as we go about our routine and we will begin to notice those we can start to get to know to begin to share God's love with."
Jason Roach, Director of Ministries at London City Mission, said, "Everyone needs the opportunity to hear the gospel during their lifetime in a way they can understand.
"There are millions of people on our doorstep, disconnected from church, who may miss out. The problem is clear, the need to act obvious, but knowing exactly what to do in the heat of the moment can seem daunting and unfamiliar. Christians are willing but need encouragement and strengthening."