I tell people that my religious beliefs are not subjects I discuss with co-workers.

You could ask him a speculative questions about current attitudes towards religious nuts living in the Mojave Desert. You know, the ones that walk around with signs saying the worlds coming to an end. And then compare those to Moses. Perhaps you could ask what type of psychological disorder someone would have after meeting a sentient burning Bush.

I usually just tell them that I have important things to tend to and excuse myself. If that doesn't end the conversation I would remind him that at work I only care to talk about work related items.

You know... I don't like advice about relgion... its nice of you to be concerned, but would you mind if we not talk about this.... OK? Thanks...

Sir, I think it is in bad taste to discuss religion or politics. Have a nice day.

Maybe say something like "Religious conversations do not interest me." Or "Thank you for considering me someone with whom to converse, but religious subjects are a conflict of interest for me." Or "I have an informed opinion that I choose not to share, but thank you." Or, "Sorry, I am on the way to a meeting."

Or, just. "No thank you."

In that context it might be best to just thank him for sharing and excuse yourself. There are times and places to do battle but the workplace is not one of them.

I usually say, “i don’t mean to be rude, but I’ve found that discussing things like religion and politics in the workplace can cause issues, so I prefer not to discuss them.”

I think there's nothing you can say to that effect which this guy will not take in a negative way. Usually with these types, anything less than agreement would be negative... maybe even an attack. And he would likely twist it into an attack when telling it to others.

Politely but firmly decline to discuss the matter and go up the chain if he persists. Or you can engage in an undoubtedly futile exchange where only one side is open to changing based on new evidence. I would probably go down that road but I'm an unabashed atheist living in New England, so....

Inform the guy that preaching in school is inappropriate and that it makes you feel uncomfortable.

I think the last part of your post is a fairly good response.
[I’m not interested in talking nor “going back to Christ”? Overall, others find me kind and friendly, that is the part of being Christian that I care about.]
If someone persists, ask them to go away and think about a pair of theological questions. And only discuss going back to Christ with you once they have an answer.
Does God not want to end suffering (ie: cruel) or is he unable to end suffering (ie; not all-powerful)?
If you could end cancer in children by snapping your fingers, you would. Are you more moral than God? If you are more moral, do you only pray to god because he is powerful and threatens you with eternal suffering (ie: a bully)?

Sorry I'm not interested. Thank you. Walkaway.

I would just tell him that you consider your religious beliefs to be a private matter and do not want to discuss them while at work, as we should not be bringing in personal matters to the work place. I did have one co-worker where I used to work insist on talking about God. After he told me I was going to hell for being an atheist, I finally lost my cool and told him his God did not even exist. So, from personal experience, I think it's best to cut off these discussions sooner as opposed to later.

just say thank you but I'm not interested

I always tell folks like that I have developed my own religion, which happens to be true, so I am not interested.

My response is: It is your god and your religion, It only exists in your brain and in your mind, it has nothing at all to do with me, it has no affect on me and I give it no second thought. Have a nice day.

Depending on the context and situation, anything from "No thanks" to "You've got to be kidding me" would be acceptable. I typically go with something like "I don't believe in Zeus either". That normally gets the point across.

Oh man oh have the same issue. This guy in a Ford pickup truck started forcefully insisting that i NEED to accept Jesus. At first I politely told him I don't want to be converted. He continued saying "oh I'm not trying to convert you, I'm just warning you what lies ahead if HE is not in your life!"
After that i had enough and I snapped.
I said "listen asshole you see that parking lot over there? Jesus is waiting there for you to get back to him and continue to suck his magic, invisible dick!"
I try and try and try harder and harder to be tolerant and I'm usually nice and able to avoid the God subject entirely...but this scumbag thought he was in the right and attempting to deny my disinterest in his shit. And that's something I can't handle.

This topic makes me so glad I no longer have to deal with workplace drama. I just can't with those people.

"With all due respect, sir, I've thoroughly investigated this Christ hypothesis and found no reasonable supportive evidence to justify any further devotion on my part. I appreciate that you've rationalized your personal experiences in your own way, but I think differently and don't share your beliefs," is what I should have said when instead I told my prosthelitizing reborn boss to kindly fuck off.

NEVER!!

I usually say I don't care what you believe but respect the fact i do not, and if that don't work, I become a savage and use the bible to make them never bring the subject again, if not outright hate me. respect goes a long way for me, and if they don't respect that fact, then I don't respect them.

I'm very openly blasphemous and reguarly share my view and hatred for established religious doctrine, saying if there god is real then he is truly a great demon and the greatest cause of suffering in the world, and I could never morally follow their teachings. But only when asked my opinion, otherwise I try to stay a wallflower, sense I think religion brings peace to some people, and I don't want to take peace away from anyone