Indexes are provided in several genres: Cross reference Bibles, Bible Dictionaries (Vine's or Nelson's), Greek and Hebrew Dictionaries, Concordances... There is one other reference source I never use, because it often is just someone's own thinking, not God's. (The Bible, inspired by the Spirit, must be understood through that self same Spirit - according to the Bible. I might add that I write essays trying to correct misunderstandings of Bible texts, Denominational Churches, and false teachers, prophets, and messiahs (like Charles Manson) .The Bible says, and you are a victim in this aspect " ...Many will follow their shameful ways and will bring the way of truth into disrepute..." - 2 Peter 2:1. Lastly, and it may be hard to find these days, regarding your ending, "Go figure. God said "Brains" not "trains" but many are still waiting at the station. Oh, and maybe other groups aren't that together - look at Britannica on Existentialism, for example. As an afterthought, maybe different perspectives develop a greater panoramic view and color in the empty spaces.