The Counter Terrorism Advice for Churches booklet says clergy should hire someone to watch the door, install CCTV and have panic alarms.
It's been created by an advisor to the Home Office who also works for the National Churchwatch.
In 12 pages of warnings, Christians are also told small parishes are most at risk of an attack from Islamic State militants.
The advice comes weeks after the murder of French priest Fr Jacques Hamel by two IS extremists.
Church doors should be bolted closed during services and a plan for what to do in an emergency should be well know, the document suggests.
"Make sure that someone is stood by the door before, during and after the service, whilst the congregation is present," it warns.
"The job of the person on the door is to delay any offenders (including those who are not terrorists) so that the police can arrive and deal with them."
The draft guidance, seen by The Mirror, is written by former police officer and Home Office counter terror adviser, Nick Tolson.
He said: "Since the French attack we have to look at the possibility of an attack on a church in this country. The risk level has gone up.
"Churches in the past were considered low risk - now we know an attack is coming... and churches are one of the easy targets. It's likely to be a knife - not a machine gun, but we are covering that too."
His advice also outlines how to deal with a disturbance during a service, how to challenge suspicious people and what to do if gunfire or an explosion is heard.
