The use of the word “you” below means any atheist reading this.
When you tell a theist that you are an atheist, especially if they are a family member or a close friend, they usually take on a defensive position. What you are telling them is that you do not believe what they believe. But that is not what they hear you saying. They hear you reject or deny the “truth” of the beliefs that you had previously held in common with them. They think you are denying the existence of their god which is “obvious” to them. It means you no longer have the same worldview as they because your view of reality is constructed differently.
I have given this subject much consideration over the years. I think their anger or negative feelings towards you is not so much that you are an atheist but that as someone who has known you for a long time (in the case of a parent – all of your life) you are a challenge to their own beliefs.
What I mean is that in order to understand how you became an atheist, they must consider their own faith. They are forced to think not just about their beliefs but why they hold those beliefs. This can be a scary prospect. I often say that atheism is the more mature position to hold. It takes a certain strength of character and honest intellectual investment to move from theism to atheism.
What you are doing in the process is knocking down the scaffolding that supports your worldview and building a new reality that is that has a completely different foundation. That construction period can be confusing and daunting because doubts creep in uninvited and can hinder the new build. (Similes –what are they like!!).
Not everyone has the capacity or the interest in challenging their beliefs and therefore not their doubts when they arise. But I think that the majority of theists are just too scared to do so. They are afraid to think about it and rush back to their church to get another dose of confirmation bias to stifle the voice of doubt they heard when they asked themselves “what made you an atheist”? They are upset or angry with you for causing them to have to confront themselves rather than for you being an atheist. They come to see your atheism as a threat to their beliefs. If someone they know could become an atheist then what is stopping it happening to them? Of course the only way they will ever understand what it means to be an atheist is if they too are brave enough to reason themselves out of the delusion.
As a rule I would advise against getting into any form of aggressive confrontation with them. What I find useful is suggesting to them to stop trying to argue with you and asking them to do this instead;
Listen, I don’t want an argument. Could you please write down your top 5 beliefs about God and why you believe them to be true, in 5 short paragraphs? I would love to study them on my own and then talk them through with you. The only rule is that you cannot claim anything is true because it says so in the Bible.
There is more to this than is first apparent. You are allowing the theist to proselytise to you and let them think you may “come back into the fold”. However when they sit down to write the 5 paragraphs they will be forced to consider their own beliefs. They will have to invest energy and develop reasoning skills so that their arguments will impress you. But what is actually happening to them is more or less the same process that made you an atheist!! They will re-read their points, criticize them, rewrite them and often get to a place of where they say “Do I actually believe this?”
At this point the doubts have “stuck”. I have known people, including Jehovah Witnesses to lose their faith with this (Socratic) method. Then you just need to tell them why you don’t belief what they believe. Don’t let them answer your questions with questions. Keep it on matters of faith and do not try explaining science or Evolution to them. Sorry, we are here to discuss why you believe these five points, that is all for now.
Strega. Reason: typo
