To add on to Nelson's comment; The great thing about communicating through writing is it gives a) you a chance to write, re-write and clarify your feelings so when you send it, it is your clear and genuine thought and b) When people are listening and they hear something that is a "trigger" for them their logical thoughts process are put on hold while the emotions take over as their body goes into full defense/attack mode. At this point they are no longer listening, they are thinking of responding while you are still trying to make your point. whether in their head or out load by interrupting you. This makes communication difficult at best and futile at most. Writing allows it all to sink in. He may have to read it several times and each time, hopefully, he will begin to see it with a reasonable and rational heart.
Lastly be respectful of his desire to be a man of faith and make sure you know how much you love him.
I think you've had very good advice. In writing to your father you will not be able to be interrupted and also your natural anxiety at having to oppose your father cannot make you appear unsure of yourself. Good luck with it. :)
My father wasn't interested in why I was an Atheist, he just knew I was wrong.
My advice don't do it unless it becomes an issue. then do where its just the two of you. prepare a few talking point, he will try to reconvert you, so have a few good arguments prepared. if it gets to the point of an argument walk away and don't come back until he's ready to respect your opinions. also don't worry about hurting his feelings, hes a big boy he can handle, worry about him hurting yours. also the only way you be prepared for questions is if your well read on the subject, read the bible and take note of the immoral parts (book chapter and verse).
I agree with Nelson. Putting it in writing could avoid a heated discussion that goes off topic and could lead to personal attacks. When I told my mother she took it really personal and started to bring up tons of unrelated things trying to figure out what she did wrong. She still doesn't really understand and thinks I'm going through a phase. I think putting it in writing seams like a good suggestion for myself. It would be a good way for my mother to get my complete thoughts before interrupting me with her sobs and wondering out loud if she gave me too much freedom or not enough.
I've never really sat down and really talked to my mom about it. She learned through discussions I had with my Aunt (her sister) on FB. Not the best way to find out I'll admit. My mom has attempted to pull Pascals's Gambit on me.. "What's it going to hurt to believe?" .. My response was, "Well, assuming for a second God exists and he is all knowing. He'll know I'm not being genuine and essentially lying. Last I checked lying is one of the 10 Commandments.So I'd rather be honest with myself and with him -- again assuming they exist. If they don't, I haven't wasted my life in believing in something that's not real." That seemed to quiet her for that moment..Since then she's asked the question again on several different occasions, I assume thinking I'll change my stance. ... Just my own experience.
I don't know your father, so I can't predict how he will react. I think it's important to reflect upon the function of telling him that you don't believe as he does. After that, you can commit to your goal regardless of the difficulties that may arise. When I told my parents, I think my goal was mainly to stop living what felt like a lie and to stop doing things (like going to mass and praying) that I no longer wanted to do. While their reaction hurt me (and them) a lot at first, it was temporary and no worse than what I felt sitting in church with them. Parents with strong religious affiliations and strong beliefs are naturally going to be scared when their children venture outside of what they consider to be a safe zone. My only advice is to be clear about what this revelation means in terms of how your behavior in front of your father is going to change (e.g. no more sunday church, no more praying, if I marry it won't be in a church, etc).
Also: If he doesn't accept it right away, that's ok. I've had friends and family members who were shocked at first, but after a while, and after many questions and re-conversion attempts, finally have accepted things.
Remember, you've had time to come to grips with your atheism, but it may be shocking news to them and they may need time to process.
I had absolutely no difficulty discussing my beliefs with any of my relatives who were willing to discuss them, though all of them were religious. They were the ones who were uncomfortable.
I told my parents:"Mom, dad, do you love me..?" They replied "Of course, you silly..!" then I told them "So, no matter what I think about god, love me like I still continue to be your son" Until now, they don't mind that I'm atheist nor my other 2 brothers, 3 sisters, nephews, nieces and other relatives. So far is more than 7 years and still they tell me that they love me every occasion. Tell him that you still love him and is not god that make you have this feeling about him is the relationship father son.
I like this approach but I've used it too many times to tell my parents when I've done something bad so it would only make them suspicious.