Is "need of religion" grammatically incorrect as opposed to "need for religion"?
Or "need of salt" vs. "need for salt"?
Due to insistence:
I'm merely going by ear here, but the usage that I was accustomed to would have me say "He is in need of (something)" and "I have a need for (something)".
The use of prepositions after need seems to have changed greatly over the last 200 years. Consider the following Google Ngram. Before 1800, the noun need took the preposition of, over half of its uses occurred in the expression in need of, and it did not take an article. When it then started being more widely used as a noun in the mid-1800s, it started taking an article, but at first it still took the preposition of. In the early 1900s, for started replacing of. Nowadays, need usually takes for except in the expression in need of.
So I would say that, except for in need of, current usage is to use the preposition for with need. I don't think I can call need of incorrect when used in the need of, since this was the usage 100 years ago, though. The construction "We have need of ..." still sounds better than "We have need for ...", but these are both becoming obsolete; current usage would be "We have a need for ...".
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