Does a free society need to be constantly on guard against religious zealots?

The US constitution seems to indicate that the forefathers were aware of how religion can take over a society and turn people into slaves. So they wanted to ensure people in the USA retained their freedom and they designed the constitution to ensure this. So this tells me that for a long time, there has been an ongoing battle between secular and religious people. Secular people want freedom - religious people want tyranny, right? Religious people think society can't be trusted with freedom and for them, the perfect society is a society with strict authoritarian rules and harsh punishment for those who have the courage to choose independence, don't they?