Again, you are being very ignorant about the motivation of atheists. You take all form of nuance out of the discussion.
Firstly, if you look at the bodies of law that exist around the world, you will find a huge religious influence. Many countries' laws forbid euthanasia, abhor abortion, even have things to say about one's consensual sex life, say things about which beverages or substances one is allowed to consume and get in your face about the clothes one wants to wear. Holland, for all it's liberalism, still has religious schools that teach discrimination of the LGBT community and still has laws against blaspheming. Go figure. We're trying to get rid of those though, but that's another story.
Atheists may take offense to certain aspects of these legislations because not having a god simply makes it silly to subscribe to certain notions. If I am terminally ill or old without any shadow of dignity or life quality, why should I not be able to end my life? The other day in Ireland a dentist died because she didn't get an abortion. She had correctly judged and diagnosed herself, asked for an abortion for two weeks knowing she was in danger, and when the foetus finally did have no pulse anymore and it was removed, she slipped into a coma and died. This happened in the EU. In 2012. The Irish should be ashamed of themselves.
Your "drinking alcohol" analogy is, again, poppycock. All atheists ever say is that god does not exist. This might have implications on their political views, and in a democracy we get to seek representation for our political views, not so? So yes, many secularists might have an agenda. This agenda might boil down to seeking a more humane and liberal body of legislation and diminishing the harmful influence of religion on our society.
Having said that, Freedom of Faculty and Freedom of Enterprise are enshrined in my Constitution. The Unie van Utrecht has had freedom of religion enshrined in it since 1579 and served as an inspiration for Thomas Jefferson et al when they were contemplating the US Constitution.
So your freedom to believe in what you will is enshrined in the Constitution. The functional separation of Church and State should become a fact, but that does not in any way infringe on your right to adopt a religion of choice or talk to your kids about that in the privacy of your own home or even the town square.
Your reasoning is so devoid of nuance I don't even know where to begin on the last question you asked.