First of all, talk of a "decision to believe" is nonsense. There is no such thing as "deciding to believe" something. Various factors determine one's beliefs. Some are rational, some (surely most) are not. We do not have the power to choose to believe. We have the power to choose whether to consider evidence, whether to examine the conclusions that we are inclined to draw, whether to investigate our sources, and so forth; and we have the power to disregard counterevidence, avoid examination of our reasoning, and in general be uncritical in our thinking. These things lie within our power of free choice. Our beliefs themselves do not.
Second, the issue that I was raising was not about beliefs per se but about the reasoning or lack of reasoning by which those beliefs are arrived at. The belief in astrology and its conclusions derives from confirmation bias and other weaknesses of the human mind. Human beings cannot help having these weaknesses, but they have a choice about whether to take account of them and examine their own thinking critically or not. It is the failure to do this, not the beliefs in themselves, that I was deriding as childish and foolish (though I am prepared to deride the beliefs as well, since no critical habit of mind can sustain them).
Third, if you were making the point that deriding someone's reasoning or lack thereof as childish and foolish is an unproductive strategy for inducing the person to be more critical--rather like trying to get someone to be more disciplined about diet and exercise by telling them how fat and out-of-shape they are--then I could grant your point. But that is not the line that you take. Your objection is that my derision is "a dangerous thing" because it is "divisive and intolerant." I am familiar with such cant phrases, but they are so evasive of determinate meaning that I would have to ask you to explain exactly what you mean by them before I could give a proper reply. For now, I will say only that whether tolerance is desirable depends on what is to be tolerated and in what manner; and I see no reason why bad reasoning should not be subjected to criticism and even derision.
Finally, concerning your points that someone's beliefs about astrology do not affect me and that I should "be careful of my words" because they "have consequences": You have some nerve to tell me that my words have consequences while you disregard or deny the dangerous effects of uncritical and pseudo-scientific thinking. Sure, astrological thinking belongs pretty low on the list of dangerous intellectual failures, as contrasted with, say, the anti-vaccination movement or the delusions of Christian right-wingers about abstinence education and the dangers of using contraceptives. But a lot of the same intellectual failings drive all these aberrations of thinking, and they cannot be condoned.
Phil Plait, author of the blog Bad Astronomy, seems to me to put the point well at the conclusion of his article "Astrology":
