Barnabas Fund's director Patrick Sookhdeo has been found guilty of sexual assault and of intimidating two witnesses.
The jury at Swindon Crown Court decided that founder of one of Britain's major Christian charities, which supports persecuted Christians and campaigns for religious liberty throughout the world, felt a woman's thighs and breast in his office.
The 67-year-old shook his head and put his head in his hands as he was convicted, reported the Western Daily Press.
Judge Peter Blair QC told him he had an "exceptional background" running the charity but that his actions had left the woman "distressed and unwell".
He said: "You were not at all well in terms of your own health and your conduct that day was poor and unpleasant.
"You are a man with an exceptional background but the witness intimidation makes the matter that much more serious.
"It left her very distressed and made her unwell.
"You will be hugely punished by these convictions and your life will change for good."
During the trial, the court heard Sookhdeo had called the woman into his office for a meeting and put his hand on her thigh.
He later called her back and asked her: "What would your reaction be if I reached out and touched your breasts?"
The woman said his behaviour was "completely inappropriate" and the incident left her feeling "stunned and shocked". "I didn't want to report it as first because I was so scared he'd sue me.
"I was sick twice on Friday [the day of the attack] and the day after I started to shake uncontrollably.
"I couldn't sleep and I couldn't eat. I was so frightened."
Patrick Sookhdeo has published more than 30 books and has made many media appearances. As well as serving as the director of the Barnabas Fund he is director of the Institute for the Study of Islam and Christianity.