"The Oneness of God" by David K. Bernard is a fantastic book that explains the Biblical truth behind the Oneness of God and the incoherence of the doctrine of the trinity.
In his book, Bro. Bernard clearly and thoroughly explains how both the Old and New Testaments support the doctrine of the Oneness of God. He does this by analyzing hundreds of scriptures, using the Hebrew and Greek words behind the translated words we know in English to give a deeper understanding of who God is. He also gives detailed explanations of how Oneness theology can respond to the verses that are commonly used to support the trinity. Bro. Bernard does a very fine job of using very clear wording in his book and avoids using complicated terminology while remaining scholarly and formal. The reliance on the Word of God, as opposed to philosophy and human thinking, makes this book all the more credible for Bible-believing Christians!
Over the course of 13 chapters, Bro. Bernard thoroughly explains how the doctrine of the trinity does not make sense Biblically and that the doctrine of the Oneness of God is the only viable explanation for who God truly is. Bro. Bernard also even goes over how the un-Biblical doctrine of the trinity came about, which is the cherry on top when compared to the thorough usage of scripture to prove the overall incoherence and contradictions of the doctrine of the trinity and the wonderful truth that is the Oneness of God!
If you come seeking to know who God truly is, either as a trinitarian or something else, this is the perfect book for you! Even for Oneness believers, this book is an excellent read because it will give you a deeper understanding of the Oneness of God and also give you plenty of scriptures to use that will aid in helping others understand the Oneness of God!