I agree with Forkbender . But its not a thing like jehovas witnesses , a sort of forced conversion , believe or be damned . If the subject comes up again just tell him the truth . If you like him you will want to help him , if he is free he will listen . Explain that you have a different point of view , and then tell him you respect his right to have a point of view . Then ask him if he respects you enough to talk about the subject . If you need to defend yourself you could tell him about the drugs in the bibles on wich it , and all religeons , are all based , the dammage that christianity has done in the past and is doing today in society , and about the fact that jesus was a jew , he didnt want to start a new religeon . That if anyone believes in jesus that they should convert to being a jew . Tell him about the ten comandments and make a comparison between them and how the christian world was and is today . Rule number one is "Thou shalt not kill" and who are the biggest killers that have ever lived , christians . Personaly if i can help someone i try to , but if they reject it its their own responsibility and i acept that . Suggestion is a wonderfull thing , if you introduce good arguments into a discussion they stick , the other person has them in their head and subconsciously they will think about it . Its a bit like seeing a car acident , or being a witness to a crime or someone beating up a foreigner or an old lady , are you going to run away or stand up and try to help . This is a choice that everyone is faced with . Do you want to freeze and stagnate in your personal development , be a coward and acept it or continue to grow . You are the decissions that you make and its better to make the right ones and not have to live your life looking back and regretting the things that you havent done or done wrong . A person can not hide from his own conscience however hard he tries .
But as i said before forced conversions dont work , dont try to hard , if he is imune to facts let him live like he wants to . If he has lessons to learn life will keep confronting him with them untill he makes the right decissions or dissapears into his own crippled fantasy world . "You can lead a horse to water but you cant make him drink"