Fourteen Free Church ministers in the Highlands have written to Transport Minister Keith Brown urging him to convert the A9 between Perth and Inverness "as a matter of utmost urgency".
The Scottish Government has already pledged to upgrade the A9 - which is the main road tot he Highlands - to dual carriageway by 2025, with a £3 billion project to convert 80 miles of the road.
But accidents on the road have led to calls for that work to be carried out more quickly.
In their letter to Mr Brown the Free Church ministers said they had seen "families being torn apart after loved-ones have died in utterly devastating circumstances" and that they had "no wish to conduct any more funerals caused by the tragic and sudden loss of life from accidents on the A9".
The ministers, from the Inverness, Lochaber and Ross areas, said: "It is our Christian duty to speak out to prevent the unnecessary loss of life, and we believe dualling the A9 would be a sensible measure for the people of Scotland - not to mention the hundreds of thousands of tourists who visit our lands each year."
Last month a crash involving two cars killed three people, including a woman and her young daughter, on the A9 near Kingussie in the Highlands.
Abigail Houston, 42, and seven-year-old Mia, from the Trinity area of Edinburgh, died in the crash which also claimed the life of Dr Mohammad Ali Hayajneh from Duisberg in Germany.
In the wake of that Professor Donald Macleod, former principal of Free Church College in Edinburgh, branded the number of people killed on the road as a "'shame to the nation''.
Leading police officer Chief Superintendent David O'Connor has also called for work to convert the A9 to a dual carriageway to be a ''higher priority''.
Plans to install average speed cameras along the road, at a cost of £2.5 million, have since been announced by Mr Brown, with the cameras - which will be installed from Dunblane to Inverness - expected to be fully operational by next summer.
The ministers, who regularly travel on the A9, said: "We accept the present state of the road in itself kills no one, and that many of the fatalities are caused by bad driving - either through confusion or by sheer frustration resulting in dangerous overtaking.
"Whilst the average speed cameras will reduce an element of risk, the 2025 complete date for dual carriageway simply isn't soon enough and we urge you to do everything in your power to fast-track these proposals.
"From 2006-2010, the most recent statistics available, 67 people have died and there have been over 1,200 collisions on the A9.
"We sincerely hope the Scottish Government is not prepared to sit on its hands until another 67 people perish, and we call on you to dual the A9 between Perth and Inverness as a matter of the utmost urgency."
Dualling the A9 has been described as a "complex and challenging" project by the government, with each section of road to be upgraded requiring in-depth design and preparation work.
A Scottish Government spokesman confirmed the letter had been received and said it would "respond directly".
He said: "This Scottish Government is the only government to have committed to dualling the A9 between Perth and Inverness and we have already invested £50 million on improvements between the two cities since 2007.
"We are determined that A9 motorists should see improvements on the route as soon as possible and we are now inviting bidders for three big design contracts for the route.
"In addition to the major improvements already done, we also continue to invest in the ongoing maintenance of the A9. This includes an annual programme of road and bridge maintenance schemes, road safety schemes and general repairs."
Highland MP Danny Alexander, who last week branded installing speed cameras along the A9 as a ''knee jerk decision'', welcomed the ministers' letter.
Mr Alexander, who is MP for Inverness, Nairn, Badenoch and Strathspey and is also the Chief Secretary to the Treasury, described it as a "very welcome addition to support for dualling the A9".
He added: "Quite rightly, the ministers are highlighting the costs of delay.
"We still have not seen any evidence that the SNP's proposal to install average speed cameras will improve the situation.
"Maybe now the Scottish Government will sit up and take notice of what people in the Highlands want."