In the First Amendment the first right enumerated is Freedom of Religion. While the first part of that clause prohibits Congress from making any law establishing a state church (which means they can’t make a law requiring you to belong to a certain religion, to attend a certain denomination, nor use tax dollars to subsidize any church), the second part of the clause prohibits Congress from making any law prohibiting the free exercise of one’s religion. For that matter, government should not compel anyone to comply or act in accordance to any belief if they do not agree with it.
In short, while we have the right to be good people, and to say or do the right thing, in order for that to be true liberty we must also have the right to do and say what may be considered unacceptable, too. That is what true freedom is. If I have the freedom to be a tolerant and inclusive person, then in a free society I must also have the allowance to be intolerant, racist, unaccepting, or whatever else one can be (as long as it is not breaking laws, such as assault, et cetera).
Milton Friedman, I think, explained it well, arguing that we if we have true freedom, government cannot force us to do what it thinks is moral.
This is why Christians are not (contrary to the arguments of the humanistic atheistic left) using law to try and force folks to be moral and righteous people. We all fall short of the Glory of God. We all sin, we all mess up, and laws by men can’t change human nature. As some have said, “You can’t legislate morality.”
That said, you can legislate morality to a point. We have legislated into law punishment for murder, lying in certain circumstances (such as while under oath, or in a way that could be considered libelous or slanderous), and we have other laws in place specifically for the purpose of influencing behavior (such as traffic laws). But, except for those obvious necessities, our moral behavior or beliefs cannot be, and should not be, legislated or be subject to judicial or legislative review.
So, if Christians cannot force their belief on someone else, because it would not, then, be a truly free society (it would be a theocracy, in that case), should other belief systems be able to use the force of law to force those who disagree with them into compliance? If homosexuals can force Christian bakers to bake cakes with homosexual messages, should they, then, be able to force Muslim bakers to do the same? Should a Christian be able to force an atheist baker to make a cake with a Christian Cross on it? Should a White Supremacist be able to use the force of law to compel a black baker to make a cake with racist symbolism on it?
Is not the First Amendment requirement of Congress not being allowed to make a law prohibiting the free exercise of one’s religion extend to whether or not a Christian may, by law, be forced to make a cake they religiously disagree with?