Is your only memory of this man in church, with so many others around? Listening to a preacher can conjure up so much imagination in children, i think you may have heard something about the devil or abuse on earth, and associated with this man's face maybe. I agree with Rock Rose , that you definitely need to talk to a therapist and to your parents about the incident, but mostly focus on how to get past your current inability to socialize in a friendly manner, at your current age and at this time.
How was your home life? was there things happening that made you feel unsupported or scared ? Were you left alone a lot as a child ?
Is your family able to sort this out with you? This has only been 8 years - it seems likely your parents or other church members could help you put a timeline on this, and determine why you have reacted so badly to this person.
I would be very hesitant to blame any current difficulties you are experiencing on a person you "instantly hated" when you attended church at the age of 10, and go on to blame this person for why you hate to be touched.
I would suggest therapy, and focus on moving forward and not trying to unravel the reason why you hated this guy at first sight - but rather, how can you overcome your current problems.
Instead of looking back with puzzling questions, can't you rely on the clear memories of others who were adults at the time who could give you clear insight?
I've heard that an analyst trained in hypnosis can sometimes unearth early memories, but you do want to beware of simply assuming this is what happened lest the analyst, in asking your about it, accidentally plant a false memory of it happening. I don't know why he led you away, that shouldn't have been allowed by your parents. In your shoes I would address these questions by seeing a good therapist.