“There are so many instances in Jesus’ preaching, even in the Old Testament, where God uses the plural to speak of Himself [to prove that God is three in one]. (He also uses the singular at times, so it is not a ‘royal’ we.)”
I am glad that you brought up this subject.
Some people suppose that we can find the Trinity doctrine in the first chapter of the Bible. They make this claim because the Hebrew word elohim, that was translated “God,” is plural, and they believe the plural pronouns in Genesis 1:26 help to support the Trinity doctrine as well.
The Hebrew word elohim is plural, but it never indicates plurality when referring to the true God. Every time elohim is used referring to the true God it has a singular meaning. Gesenius calls it “the plural of majesty” and the Brown-Driver’s Brigg’s Hebrew Lexicon says that when it refers to the true God it is “plural intensive” with a “singular meaning.”
Furthermore, the word elohim is used in the Bible in places where it could not possibly be referring to a plural being. For example, God said to Moses, “See, I have made thee a god [elohim] to Pharaoh: and Aaron thy brother shall be thy prophet.” (Exodus 7:1) Was God saying that He was going to turn Moses into a trinity? Obviously not! God would not have us believe that Moses is a plural being. For other examples read 1 Samuel 5:7; 1 Kings 11:5, 33; 18:27, etc.
As indisputable evidence that elohim has a singular meaning when referring to the true God, please consider this: whenever New Testament writers quoted from the Old Testament they used the singular Greek word theos to denote the true God as a translation of the word elohim. This is also true of the Greek translation of the Old Testament, the Septuagint. This proves, beyond a shadow of a doubt, that elohim has a singular meaning when referring to the true God. If elohim really indicated a plurality in the true God, then the New Testament writers should have been consistent and used the plural form of theos (qeoi, qeoiV or qeouV) when speaking of God, instead they used the singular, every time, even though they used the plural form 8 times when referring to men or false gods. (You can read these for yourself in John 10:34, & 35; Acts 7:40; 14:11; & 19:26; 1 Corinthians 8:5; and Galatians 4:8.)
Regarding the plural pronouns in Genesis 1:26, the pronouns are plural in the original Hebrew, forcing it to be translated, “God said, let US make man in OUR image, after OUR likeness.” Those who claim this verse teaches a trinity point out that elohim is plural and the pronouns are plural, therefore there must be a plurality in God. If we are to accept this explanation we would have to translate it, “GODS said, let us make man in our image, after our likeness.” This translation would do injustice to the true meaning of elohim, and it would have three Gods speaking in unison, saying, “Let us make man in our image.” Is that what God is trying to tell us? Did several Gods create man, or was there just one?
Those who promote the idea that Gods said, “Let us make man,” run into a big problem in the next verse, because all of a sudden the pronouns switch to singular, both in Hebrew and in English, while the plural elohim is still used. Why was there a change? The next verse says, “So God [elohim] made man in HIS own image, in the image of God [elohim] created HE him.” If we are expected to believe that Gods are speaking in verse 26, to be consistent we must believe that Gods are being referred to in verse 27, but instead of plural pronouns the Bible changed to singular pronouns as if only one person was referred to.
Now, there’s a very simple explanation for this. The use of plural pronouns after a singular noun does not indicate that the singular noun should really be plural. For example, let’s suppose the president said to the attorney general, “Let us make a law.” This wouldn’t indicate that there are two presidents just because he used a plural pronoun. The plural applies to the two who will be involved in making the law rather than to the president. In like manner, the “us” and “our” in Genesis 1:26 applies to the Two who were involved in the creation of the world rather than to the one who was speaking.
The Bible says “God… created all things by Jesus Christ.” (Ephesians 3:9) It is obvious that the God in this verse is someone other than Jesus Christ. And according to Hebrews 1:2, God, the Father, created all things by His Son.
Now, we can know for sure who is speaking in Genesis 1:26, and whom He is speaking to. God, the Father, said to His Son, “let us make man in our image.” Remember, Christ is “the express image” of the Father, so anyone created in the Father’s image is automatically created in His Son’s image.
I am glad you mentioned the use of the plural by Jesus in the New Testament. Jesus used the Greek word, theos, in the singular form, many times in the New Testament. Every time He used this word in the singular form He was referring to one person, and one person only, God, His Father. Also, every time He was referring to God, He used the singular pronouns which were translated, He, Him, His, Thy, Thine, and Thee. Every time Jesus included Himself when He was speaking of God, He used the plural pronouns, we, us, and our. Here are some examples: John 14:23; 17:11, 21; etc.
So, to the best of my knowledge, God never referred to Himself using plural pronouns, or nouns with a literal plural meaning.
I hope this helps to clarify this issue.