Arguing against religious beliefs is expressing your own religious beliefs. If someone says "God loves you all" and I say "a loving God wouldn't let children suffer and die", We are both expressing our religious beliefs.
The only exceptions to freedom of speech are things like uttering threats, Hate speech, And libel (lying about someone in a way that hurts their interests). It's pretty easy to express disagreement with religious beliefs without doing any of those things.
Nothing is above criticism and one of the last things that should be above criticism is religion. The idea that something should be untouchable because it makes a certain population feel good or is sacred to an individual is ludicrous, Especially considering the direct harm religion can cause. Criticizing this is not hate speech; it's addressing a problem. Many religious beliefs are usually considered morally good, Especially those that focus on themes of love, Forgiveness, Etc. But there's a vast number that are also quite harmful, Or at least in a grey area. Religious attitudes concerning certain scientific theories, Attractions, And histories should not exist without rebuttal. Until religion can objectively prove itself true, Then on what grounds does it deserve special untouchable treatment?
There are some freedoms clearly spelled out and there should be some which can be deduced. So we have a Freedom of Speech and Freedom of Religion and there is Separation of Church and State -- I'd say we do have a Freedom From Religion, Which permits to write against it.
In the U. S. , We have the right to our own opinion and the right to voice that opinion. We also have the right to make claims against anything as long as we can validate those claims. Unfortunately, Today, What begins as opinion tends to progress into a claim. Hypothetically, A senator states, As an opinion, That they think a person is guilty of a crime. The media can take that opinion and state "According to this senator, That person is guilty" turning opinion into something that can easily be seen as a proclamation. This is just one of the ways the media tends to twist facts.
Thing is, It does not matter what topic it's about. The same freedom of speech should apply. This should also include opinions about race. Sadly, Some people want to declare any unpopular speech as "hate speech" even if it does not make any proclamation or if it's not intended to incite violence. Not that I agree with any racist beliefs but just that they should still have the same right to voice their opinion. If we allow one type of speech to be prohibited, It sets a precedent to outlaw any unpopular speech.
To voice your opinion is one of the most important things that a human being could need in life. But not when that opinion has a direct negative impact on the mental well being of another human.
If someone says "God loves you all. " and you spit in his face and provoke feelings of negativity towards that person, You are directly contributing to his mental well being.
If a religious person wants to share his beliefs with you, He is not trying to influence you negatively. He is trying to share his belief in the hopes that it can bring you the same joy that he felt when he became a believer. His actions may not always be appropriate but the feeling behind it is to help you. Regardless if you need it or not.
But to talk to a religious person, Outright slam his beliefs and then laugh at him. That is not ok. You have not delivered your opinion, You have slammed his. That is not freedom of speech, That is hate speech.
To physically go out of your way to oppose someone else's faith is also hate speech, Because it is done out of spite. You want him to get angry and you want him to fight you, You are instigating aggression.
As Ettina said, You can say "a loving God wouldn't let children suffer and die". You are allowed to say that, But there are certain limits to expressing your feelings on religions. For example, You cannot discriminate people for their religious beliefs, Or religions. So this debate can come up to an agreement that there are certain limits to your rights.