As a realist, I know that exposure to religion will be routine for my children during their lives. I do not try to keep that exposure away from them. It would be a futile attempt to keep it from them and brainwashing them with Atheism would make me just as guilty as the theist that brainwashes their children and indoctrinates them into their religion.
There are instances where I will prevent certain exposure, of course. I will not let my children go to a church that espouses hatred. I will not let my children attend certain events affiliated with certain denominations because of some things that they do that I deem to be unethical.
My in-laws isolated their children from the world out of fear that they would not believe in God if they saw how the world really operated. In my eyes, that was mental child abuse. Their daughters lacked preparedness for the world and reality when they left home. They were dependent upon others and scared of their own shadows. That is no way to raise children so I would never raise my children in the same way.
All I can do is to help my children understand what is exposed to them. I can explain to them why people believe what they do and help them to become critical thinkers. I can give them everything they ask for when it comes to education. If they leave my arms knowing how to think on their own two feet and how to use the critical thinking skills, logic, rationality and reasoning that their human brains allow them to do, then I have achieved something. If they go on to believe in a god, then so be it.
One thing that I have done for my children is to teach them as much about religions as possible. The important thing for them to understand is that this is not a black & white; Atheist versus Christian world. They need to know that there is a rainbow of beliefs and religions out there.
They have learned about Hinduism, Judaism, Paganism, Wicca, Christianity, Islam, Atheism, Shamanism, Buddhism, and others. When my children ask for information on a religion then I give it to them. I am not afraid to expose my children to different religions because I have also taught them the critical thinking skills they will need to make an educated decision about this matter.
My children regularly attend a Unitarian Universalist fellowship and they have gone to Vacation Bible School with their friends. My children ask questions about different religions and different beliefs. I do not push my non-belief on them, but I do answer questions they have honestly.
My children know that I am an Atheist. I do not lie to them. My children know my views, but they also know the views of others. When they ask about something, we tell them what everyone believes. We tell them what Christians believe, Muslims believe, Jews believe, Wiccans believe and what Atheists do not believe.
By exposing my children to all religions instead of isolating them away from religion, I feel that their odds of being critically thinking and rational adults actually increase. They already know that there is not “one true god,” but a bunch of different religions all claiming the same thing about their deity.