A bus driver kept his passengers waiting for 20 minutes after refusing to board the vehicle because it featured a gay rights message on the side.
The unnamed driver would not get on the X78 from from Rotherham to Sheffield, which bore a billboard for gay lobby group Stonewall, reading: "Some people are gay. Get over it!".
Passengers sat and waited while the driver argued loudly with colleagues and customers.
Among those on the bus was Rebecca Neill, 25, from South Yorkshire, who had boarded the 5.25pm service at Rotherham and had just taken her seat when the row began.
She said: "Once the driver had let us on the bus he was meant to be swapping with another driver, but when his replacement wouldn't get on they just left us there while they had an argument outside.
"There were quite a few passengers arguing with him and several drivers as well. Someone was shouting at him: 'You can't do that, it's disgusting.'
"Then another driver got on and explained what was going on. He apologised and said that the poster wasn't acceptable to this Christian, but that he didn't agree with what the guy was doing."
Eventually, the next X78 service arrived and its driver swapped buses with the protester.
By then, Rebecca had already missed a connecting tram at Meadowhall shopping centre in Sheffield.
She said: "I just thought it was disgusting, I would never say: 'I'm not getting on your bus because you believe in God and I don't.'
"He's a bus driver - he's going to come across all sorts of people. Does he seriously think he has never had a gay person on his bus?
"I think it's wrong that he can cause such a fuss while people are trying to go places."
A spokesman for bus operator First Group would not divulge what action - if any - had been taken against the driver.
He said: "We are aware of an incident involving one of our drivers refusing to drive a bus at Rotherham Interchange.
"We have spoken to the driver in question and the matter has now been resolved. We would like to apologise to any customers that were affected during this isolated incident."
Stonewall information officer Louise Kelly said: "Passengers in Rotherham can rightly expect bus drivers to do the job they pay them to do - drive buses.
"If they are unwilling to, perhaps they should look for another job."