You can put double quotes around a phrase and search for exact phrases. The search engine actually takes the stem of the words you put in the search box and searches for all forms of that word, so "god's love" would find phrases with god, god's, godly.... love, loving, loves in them.
You can do this: "old testament spirit"~10 and that will find places where those three words are within 10 words of each other. If that found nothing, you could change it to ~20 or ~30. That should help you look for some topic like the ministry of the holy spirit in the old testament.