Gary Edwards, 35, is believed to have been drug free for more than six years when he died after relapsing and taking drugs which contained fentanyl last November.
-> Christa Ackroyd: Why I defend women's right to wear the burqaAn inquest at Wakefield Coroner’s Court heard Mr Edwards, of Chapel Allerton, Leeds, died as a result of fentanyl and morphine toxicity.
Speaking after the inquest, his mother Debbie Edwards, 56, said her son went off the rails as a child after his father Ray died aged 52 when Gary was ten-years-old.
She said he started using cannabis aged 15, went on to use cocaine and by his late twenties he had become a crack cocaine and heroin addict.
When he was 29 he went into an 18-month rehabilitation programme in Scotland with the Christian Teen Challenge organisation.
She said he became a youth leader aged around 32 with the Bridge Street Community Church in Burmantofts, Leeds.
Mrs Edwards said he raised around £6,000 to set up the Mission to Calais organisation to help children living in the former Jungle refugee and migrant camp in France.
He also visited Romania on three occasions as part of a project to help build and maintain school for underprivileged children.
Mrs Edwards said: “Gary had a real zest for life.
-> Tornado blows through Yorkshire as Storm Debby hits“Everyone who met him couldn’t forget him because he was such a big character and so full of life.
“His passion was youth and trying to stop kids making the same mistakes as he did.”
Mrs Edwards said: “He had a relapse and that was it, it’s killed him.
“Nobody knows what they are taking anymore. Gary would never in a million years have taken anything that he thought would kill him.
“One tiny bit of fentanyl and you have got no chance of surviving.
“The dealers might as well go around sticking a gun to people’s heads and shooting them.
“I would urge people never to take any illegal substances because you never know what you are taking.”
Mrs Edwards said when her son was younger she always feared receiving phone call informing her of his death.
She added: “After six years those fears had gone.
“After he went into rehab I never thought I would be in that situation again.
“But addicts do relapse. One fix killed him. My whole world just fell apart.”