One text that is commonly quoted by Unitarians ad infinitum and ad nauseum is the creed of Judaism in the TANAKH, quoted by Jesus within the New Testament. Let's look at the texts:
Deuteronomy 6:4: "Hear, O Israel: The LORD our God, the LORD is one."
Mark 12:29 ""The most important one," answered Jesus, "is this: 'Hear, O Israel: The Lord our God, the Lord is one."
In Deuteronomy 6:4, the word used within the context of the passage is "echad", which depending on it's context can either refer to plural oneness or singular oneness. For example Adam and Eve become echad in Genesis 2:24 or one and the Tabernacle parts become echad in Exodus 26:6.
Now the Unitarian will assert that echad in the context of Deuteronomy 6:4, which they believe that disproves the Trinity. Their dilemma they create is if they can show that Deuteronomy 6:4 is singular and not plural, the Trinitarian position collapses.
Well the question is, Although I am willing to grant that echad is singular in the context of Deuteronomy 6:4 and I am inclined to think it is, what does it actually mean?
The answer is simple, It simply means that there is only ONE God, that's all it means. It is not a proof text for the Trinity, nor a proof text against it.
As I stated before in my response to Tovia Singer. The Trinity teaches that in the very being or essence of God, there exist Three Distinct persons, Not three beings in one being or three persons in one person. There are not three seperate Gods, but one Eternal God which the TANAKH and the NT make very clear.
In light of what Deuteronomy 6:4 ACTUALLY teaches, not what Unitarians want it to teach and even what Trinitarians assert, We can see the Trinity is neither proven by the Shema nor refuted, because both Trinitarians and Unitarians ARE BOTH MONOTHEISTS. The Shema is a creed of Monotheism, not of Unitarianism.
Anthony Buzzard and other Unitarians can quote this text AD INFINITUM AND AD NAUSEUM, it doesn't prove their point. Monotheism, doesn't prove Unitarianism, because Trinitarians like myself ARE MONOTHEISTS. Any claim we are not monotheists is based either on ignorance of the Trinity or a deliberate distortion of it.
Hope this article has been of help to you.