I recently received a copy of this document, "Should You Believe in the Trinity", from a coworker after we had eaten lunch. Over lunch we had briefly discussed the trinity. I plan to give this apostasy back to him after one reading.
The claims of this document are evidentially and historically incorrect. More than that, I find the authors use of source documentation intellectually dishonest. The use of misquotes. It uses ellipses to hide words like "however", "but", and "therefore" to present a completely different point from that being made by the source document. For example, it quotes the Encyclopedia Americana as stating that the doctrine of the Trinity is considered to be 'beyond the grasp of human reason (p.4). However, here is the full quote from the source: "It is held that although the doctrine is beyond the grasp of human reason, it is, like many of the formulations of physical science, not contrary to reason, and may be apprehended (though it may not be comprehended) by the human mind."
"Should you believe it?" –Yes, because it is implicit throughout the Bible. Like the word trinity, the words omniscient and omnipresent are not explicit in the Bible either. But no one claims that means the Bible says God isn’t omniscient and omnipresent. Matthew 28:18-20 "And Jesus came to them and spake unto them, saying, All authority hath been given unto me in heaven and on earth. Go ye therefore, and make disciples of all the nations, baptizing them into the name of the Father and of the Son and of the Holy Spirit: teaching them to observe all things whatsoever I commanded you: and lo, I am with you always, even unto the end of the world. (New American Standard)"