That rule certainly went out of the window in 2018 as a number of believers headed to the top of their professions thanking God in the process.
Let's take a look (click on image for more):
Chris Pratt
"God is real. God loves you. God wants the best for you, believe that - I do"
Chris Pratt's MTV 'Generation' award speech went viral in June - not just for his toilet talk.
Anne Hegarty
"I was offering up prayers for Emily that she's going to be OK and she's not going to freak out".
Contestants on I'm a Celebrity were seen praying on screen ahead of a trial including snakes.
Tyson Fury
"I don't know how I got up...I had a holy hand upon me, that brought me back."
In one of 2018's greatest sporting moments, Tyson Fury managed to return to his feet after taking a monster punch in his heavyweight boxing clash.
Piers Morgan
"I know many people don't believe in any God or religion...and I respect that - all I ask in return is for my beliefs not to be rudely disrespected."
Never one to hold an opinion back, TV presenter Piers Morgan hit out at the Met ball's religious theme.
Sope Aluko
"During breaks we shared our testimony of how we got to where did and most of the people were testifying to God's miracles, it was almost like church."
The Black Panther actress spoke of the amazing community of believers on set.
Lewis Hamilton
"Anything can happen any day, but I feel God has his hand over me,"
Lewis Hamilton stormed to victory in this year's formula one championship with the help of God.
Michael Gove
"One of the things I find of most people who have a personal faith is it makes you more conscious of your fallibility."
With Brexit looming, 2018 was a big year for Michael Gove. Speaking at a Theos event he described how his faith helped him.
Ann Widdecombe
"I mean, when I consider that I'm a pensioner and a defender of the unborn and traditional marriage and the Roman Catholic Church, all of which are unfashionable views, and that I am the scourge of political correctness and general snowflakery and emotional incontinence, I think it's surprising that I'm still here."
An unlikely success story of 2018 Celebrity Big Brother, Ann Widdecombe was as surprised as anyone.
Stormzy
"I know that a lot of people, when I give the glory to God, it seems such a strange thing, but if you know God, you know it's all him."
After winning big at the Brits, rapper Stormzy was keen to thank God.
Sir Cliff Richard
"It felt like I was in thick mud, I can't describe it any better - a hole - and I didn't know how to get out. I didn't know what to do. Thank God for friends and thank God for God."
Sir Cliff Richard finally cleared his name in 2018 and spoke often about how his faith helped him through the ordeal.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.