Over the past year I have heard many pastors encourage people to read books written by men who were dead. Authors such as C.S Lewis, Charles Spurgeon, Jonathan Edwards, Martin Luther, etc. A couple of months ago I was in my parents den looking through some of their books and I found "Spurgeon on the Holy Spirit", so I borrowed it and have been reading it for a month now. It is small (page number wise) but extremely thick (depth wise). In the 4th Chapter: Personality of the Holy Spirit, Spurgeon mentions the importance of the Trinity in the Gospel.
"A Gospel without the Trinity! It is a pyramid built upon its apex. A Gospel without the Trinity! It is a rope of sand that cannot hold together. A Gospel without the Trinity! Then, indeed, Satan can overturn it. But give me a Gospel with the Trinity, and the might of hell cannot prevail against it. No man can anymore overthrow it than a bubble could split a rock, or a feather break a mountain in two."
I will post more and more quotes, as I come upon them.