Well, I'm the non-religious child of non-religious parents, so I'll try to answer some of your questions.
>>Recently atheists often complain that people are religious for no other reason because they were brainwashed in their childhood.
I wouldn't use the word "brainwashed", but it's quite true that most religious people follow the religion of their parents, mainly because that's the religion they were brought up in.
>>Therefore they wanna forbid Christian parents their right to educate their children with Christian religion.
That isn't actually true. At least some atheists are opposed to the indoctrination of children, and quite a lot are against state funding of religious schools, but I've never met a single atheist who wants to "forbid" parents from teaching their children their own religion.
>>You taught your children that being religious is wrong and a delusion.
I don't think I'd teach children that. My parents are non-religious (functionally atheist), and my mother is strongly opposed to organised religion, but nobody ever used words like "delusion" to me. I'm actually pretty relaxed about the whole thing.
>>Nevertheless and despite your efforts to keep your child away from religion, your child grows up and still wants to become a Christian.
I'm not sure what you think life in a non-religious family is like. I wasn't "kept away" from religion. Religion happened around me. Our neighbours and many of my friends where I grew up were fairly religious Christians. I also had Muslim, Jewish, and Hindu friends and acquaintances when I was slightly older. It was the 70s and early 80s in Canada, so we still had some Bible reading and so forth in school. It just wasn't all that interesting to me, and my parents didn't participate, so I never developed any real religious beliefs or connection with a Church-based community.
The only thing that I'd really want to be different for my own child is the Bible in school bit, as I am very much opposed to public schools pushing a religious point of view.
>>Wouldn't you wanna sue those who promoted Christianity to your child , thereby rendering all of your parenting pointless because you failed at preventing your child from being religious ?
No. I hope that I would bring up a child capable of rational thought and conscientious choice. If that means that s/he becomes religious, then so be it.
>>Can you reconstruct now how religious parents feel when Atheists promote their sinful agenda already to their children, in order to bring them away from religion, ?
What is this sinful agenda we're promoting, exactly? My parents were pretty big on moral values and so am I. Christians knock on my door all the time to promote their religious agenda, but so far, not even one atheist has turned up.
Anyway, no, I can't. If I joined a religion, my atheist parents would still be my parents.
>> Are you aware of the fact that doing so also undermines the natural bond of love and trust between a child and his/her parents ?
Nonsense. This is nothing more than a rant about how religious people can't stand the fact that people don't agree with them. Srsly, you need to get over it.