Furnish, who attended the funeral on behalf of his partner Sir Elton John, said Mr Cowles had been in bits since the singer's sudden death.
"I think sometimes God wants the good pure souls early and that's the way I think of it. I can't make sense of it any other way because he was such a good man," he said.
"The world is a much less brighter place without him."
Furnish also slammed media speculation surrounding the popstar's tragic death.
"A lot of the things that have been written are deeply insensitive," he said.
"I think they are ignorant, I think they are ill-founded and I think they should allow him to rest in peace.
"The Coroner's ruling was decisive.
"And regardless of how anyone died, Stephen was a wonderful man and I think we should remember that and celebrate the great things he brought to the world."
Sir Elton, who is on tour, sent a bouquet of yellow flowers left just outside Laurence O'Toole Church, close to the main entrance.
Furnish said the celebrity couple introduced Gately and his partner because they were both single and he thought they would get on well together.
"They met for coffee and really got on like a house on fire," he said.
"They were genuinely happy together and loved all the same things in life.
"They had a lot of great times together."
Furnish spoke of the how the death has affected Mr Cowles.
"I can't think of more horrible circumstances in the world than being in your home and waking up the next morning and finding your partner dead," he said.
Furnish revealed his best memory of Gately was when he revealed he won a disco dancing competition when he was younger - and then did a dance display at their home in the south of France for a group of people he barely knew.
"He was just so full of life and so full of energy and positivity," added Furnish.