Here's what Richard Dawkins says in The God Delusion:
The God of the Old Testament is arguably the most unpleasant character in all fiction: jealous and proud of it; a petty, unjust, unforgiving control-freak; a vindictive, bloodthirsty ethnic cleanser; a misogynistic, homophobic, racist, infanticidal, genocidal, filicidal, pestilential, megalomaniacal, sadomasochistic, capriciously malevolent bully.
Now, Dawkins himself has commented on this (though I can't immediately find the provenance). What I'm about to say is not, therefore, very original, but I do know that Dawkins more-or-less agrees with it - or at least some of it.
Some people doubtless think that the above quote is "shrill" or "strident". I say that those people are tone deaf. The tone is, above all, that of someone delighting in the English language and inviting us to do likewise, as he locates all these adjectives, many of them polysyllabic, though the rhythm of the prose (try saying it aloud) is controlled by the fact that they are not all of the same length. The delight is heightened by the sense that we have as readers of the sheer thoroughness of this denunciation, and by its precision and accuracy: by a sense that Dawkins could justify each of these very specific adjectives (and the nouns they attach to) individually, if called upon to do so. Whatever this passage is, it's not Dawkins playing tennis with the net down. It's exuberant yet disciplined.
The total effect is not just that of intoxication with the language, though it's certainly that as well; it is, let's say it, funny. Indeed, when Dawkins reads the passage out loud to audiences they laugh at it. That's his aim.
There's a seriousness about it, too, of course. Once again, the joy of the language and the humour it produces rely on the thoroughness and precision (and accuracy) of this denunciation of the Old Testament God. A serious point is being made here, but also in a way that celebrates our ability to make it in just this way, and partly for that reason it invites our laughter.
There's a great deal more that can be said about the passage, including, yes, the fact that a certain disrespect for the Old Testament and the religious significance of the passage is conveyed. God, as described in the Old Testament is being revealed not just as monstrous but also as absurd, and we are invited to feel and share the absurdity as we laugh at the wordplay. There's an iconoclasm about it, of which we are conscious - perhaps even uneasily, but perhaps not so much - even as we laugh.
The tone of The God Delusion is not strident. Sometimes it is passionate and blunt, more often it is urbanely humorous, but it can also be thoughtful: carefully making distinctions and even concessions, while identifying what the author invites us to regard as the important and irrefutable nuggets of truth. Dawkins is, to pick up on some of my previous post, a master of the English language, and there is always much going on in any passage that he's written which resists a reductive description as "strident" or "shrill". Of course, if you start out unsympathetic to him, with a closed mind, you may miss all this, all the humour, the cajolery, the careful seriousness of purpose, but it's all right there in the choice of language.
When Dawkins is described as "strident" or "shrill", one response is to say, "Who cares? All that matters is the cogency of his arguments." But this is an unsophisticated response. People are always going to be interested in discussing the sorts of things I've pointed to in this post - and even if they're not comfortable discussing it, they will encounter language working in these complex ways. And it will do its work on them, one way or another.
It might, for one thing, sometimes make them laugh out loud.
A better response to someone who complains about the tone of such a passage is not:"Tone doesn't matter." It's: "You're tone deaf."