Which many theists raise,claiming that any criticism on their religious beliefs (and yeah,even harsh) is an insult and a suppression of their freedom.

Like if i say that your belief in the judeo-christian god is a load of bollocks, i am insulting you.Watch it, not because of the words i use,that is irrelevant, and is determined by how well you know the person you are speaking with.
If i start a conversation about god, i will make it crystal clear that his beliefs are childish immature and blatantly unscientific,using the appropriate vocabulary,but still letting him/her know about my honest opinion.

Why should we show ANY kind of respect to supporters and propagandizers of ridiculous ideas?

I am not talking about restricting their freedom to do so,i am talking about the way in which to confront them.Verbally and with arguments i mean.

Which many theists raise,claiming that any criticism on their religious beliefs (and yeah,even harsh) is an insult and a suppression of their freedom.

They're wrong. They make take it as an insult, but that has no bearing on the validity of the criticism. As for criticism = suppression, that's hysterical nonsense, and it's especially ironic coming from theists.

Why should we show ANY kind of respect to supporters and propagandizers of ridiculous ideas?

Don't ask me. I'm not the sort to handle the believers with kid gloves. I am always ready and willing to point out the absurdities inherent within religious belief.

I am not talking about restricting their freedom to do so,i am talking about the way in which to confront them.Verbally and with arguments i mean.

I think that should be entirely up to the individual in question.

I would suggest you counter them with saying that; On the contrary, when you critisize someone with an embarrassingly wrong belief, you are actually performing a truely friendly gesture. For it means you want to take the effort to better your fellow man. But if you keep silent, you are in fact being very selfish, for not taking on the due belligerence which is your duty, even though it be a bit stressful.

For the sake of trying to have friends, I tend to tone down my anti-theism in public.

I think there's a problem if people see you as highly "disrespectful" and won't want to associate with you - don't you want to try to "turn" people rather than just gloat over them?

Criticism of an idea is not criticism of a person, though it may be interpreted as such.

We should respect a religious leftist as a person. We should not respect their ideas for many, many, reasons.

The first step is to explain the difference between critique of an idea and critique of a person. You have the freedom to critique any idea you wish - including one as insane as religion.

Second, explain the workings of responsibility. As a religious person, they must assume responsibility for their beliefs and therefore must defend them when confronted. Most religious individuals cannot, or choose not to, do so. They retreat to the argument you have mentioned, and hence you must repeat the steps.

NoXion is absolutely correct that one ought to feel free to dismantle any religious idea one runs into. The strength of one's argument is rooted in reason, and history. The strength with which one wishes to deliver the argument ought to depend upon the individual at hand.

I tend to approach new users with more caution and lighter words, whereas seasoned users I will simply go line-by-line with their arguments.

- August

I respect them as long as I'm not challenged for being athiest , then its fair game .

Then how about irrational fanatic fundies?

(too many hours of atheist+anti-theist media have spawned a unparalleled antitheist frenzy upon me)