The head of LifeWay Christian Resources is urging pastors to adopt the Billy Graham Rule to ensure that they do not fall into moral failure.

The rule was made popular by late evangelist Billy Graham, who said he avoided being alone with any woman who was not his wife.

LifeWay president Thom Rainer said that although some people mock the Billy Graham Rule as archaic or legalistic, the #MeToo movement has shown it to be 'really wise'.

In a video message to the church, he warned that if pastors did not understand the dangers of being alone with a person of the opposite gender, they risked ruining their lives and their churches - even if nothing untoward actually happened.

'There could be no hint of impropriety except for the fact that you are alone, but what happens if someone sees you alone with [a person of the opposite gender] and draws conclusions?' he said.

'The Bible teaches us to avoid the appearance of all evil, not just to avoid evil, and so that means that we should not put ourselves in any position not only where we may have temptations or we may be putting someone else in a compromising position but also where others could perceive it that way.'

He said one man had reached out to ask him if it was ok to take a 10-minute ride to the airport in the same car as a female colleague.

Rainer said even this was a compromise too far and that Christians of the opposite gender who are not married should avoid travelling together at all costs.

'You make one exception and you just open the door for other exceptions and though I may sound a bit legalistic and overbearing, I said no...I simply have this iron clad rule,' he said.

Rainer said many of the compromising situations that have 'come back to haunt' pastors and Christian ministry leaders could have been prevented if they had just followed the Billy Graham Rule.

At LifeWay, Rainer said he even changed the office doors to ensure they had windows in them as a way of improving visibility and accountability.

He concluded by warning that one of the most dangerous things for a Christian leader is the thought that they will never fall into moral failure.

'Let's not be stupid and worrying that we're being a little overcautious and maybe crossing the line to err on the side of caution. Let's be smart,' he said.

'We're living in a day and age where this is coming forward and that is good. Don't be that person who thinks it can never happen to me. Usually that is the person that ends up regretting the decision that he or she made.'