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I haven't heard the particulars of this technique of the saints, but I suppose it might entail getting the permission of the subject to let you place the rosary over his head, otherwise you'd be risking a fight breaking out. Like if you tried to do that with any of the growing number of publicly professing satanists these days, it would probably come to no good.
Even a protestant so-called evangelical would likely fume and scoff at such an idea, forbidding you to come near with your rosary.
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