An evangelical Christian lecturer who helped run his local church youth club was convicted yesterday of sexually assaulting a schoolboy he befriended through an internet gay chatroom.

Judge David Morris told Anthony Gray, 30, of Bicester, Oxfordshire, that it was inevitable that he would receive a lengthy custodial sentence.

He added: "I have come to the view you came to Cardiff with deceit in your heart and lust in your loins."

He remanded Gray in custody for reports and ordered him to register as a sex offender.

The jury heard how Gray, who studied theology at Exeter and Oxford universities, met the 14-year-old boy after logging on to Gay.com and they chatted online about 20 times before meeting in Cardiff.

Gray, now the father of a six-month-old daughter, was due to go to the city on a business meeting in April last year. The meeting was cancelled but he made the 200-mile round trip and met the boy at the city's central railway station. They went to a cinema and then booked into a hotel.

Gray, who denied the charges, said that in the hotel room they had only chatted about the boy's struggle with his sexuality. But the judge said it had been "pre-planned" and that he had "wreaked his sexual satisfaction on a young and vulnerable boy knowing full well he was under age".

Gray admitted he had told the schoolboy during their on-line chats that he was a 22-year-old openly gay man and said he wanted to advise the boy about his sexuality.

Gray, now a lecturer for the Universities and Colleges of Christian Fellowship, said he had started struggling with his sexuality five years ago after seeing images of gay pornography on a borrowed computer.

He described his home life as "happy and content" but found that he was excited by the gay pornography.

The court heard that he bought gay porn magazines and videos on trips to London and Oxford and hid them from his wife in the attic. When police raided the house after his arrest in August they found 33 gay videos, hundreds of magazine cuttings and 3,000 gay images of teenage boys downloaded on to his computer.

Prosecutor Greg Bull described Gray as a "Jekyll and Hyde" character who appeared to be a respectable citizen. "But he had deeper, darker motives for seeking out young boys," he said.

The court heard that the boy told of the meeting when, three months later, his parents questioned him about his internet phone bill. In evidence, the boy, who had been given the computer with a dedicated phone line to help with his homework, said he was "confused" because he thought he might be gay. "I confided in my friends but not my parents. I was trying to speak to people of my own age who would understand me. I gave [Gray] my telephone number."

After the hearing, the boy's mother said: "I would warn other parents to watch what their children are doing on the computer."

The case comes after seven men were jailed for their part in the Wonderland internet paedophile ring.

Michele Elliott, director of Kidscape, said recent cases showed the urgent need for restrictions on the internet.