In its comment on 1 Corinthians 8:6, the second edition of the The Ignatius Catholic Study Bible reads:
The Ignatius Catholic Study Bible - 1 Corinthians 8:6
Paul distinguishes the Christian faith from paganism, which venerated many gods, and from Judaism, which declined to accept the messianic Lordship of Jesus. Paul alludes to the monotheistic creed of Deut 6:4, but he applies its two divine titles to two distinct Persons. 'God' is linked with the Father, the divine Source from whom all creation originates, and 'Lord' is linked with Christ, the divine Mediator through whom all things were made. This is one of the clearest Pauline passages to assert both the deity and divine activity of Jesus Christ (Col 1:15-17).
Above, the Ignatius Commentary asserts that 1 Corinthians 8:6 "is one of the clearest Pauline passages to assert both the deity and divine activity of Jesus Christ", because it applies the term "Lord" (Yahweh) from the Shema (Deuteronomy 6:4) to Him, while reserving "God" for the Father. This is a common argument in modern Trinitarian apologetics, and is covered in its own article here.
The two passages in question are:
Deuteronomy 6:4 (NRSVUE)
4 "Hear, O Israel: The LORD is our God, the LORD alone.
1 Corinthians 8:6
6 But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him.
Notice that, on the surface, the passages are actually very different. They can both said to be creeds, and can both be said to teach that there is one God, who is Yahweh (the Father). But, the assertion that the Yahweh of the Shema has been in some sense detached from the "God" term of the Shema, such that it now refers to Jesus, and "God" refers to the Father, is an extraordinarily controversial assertion, which cannot be justified in context at all.
Such a reading of this passage would have the Apostle Paul be stating that for Christians, there is "one God", the Father, and "one Yahweh", Jesus Christ. But, Yahweh just is God - that is the entire point of the Shema. "Yahweh" is the name of the one God that Christians worship, which, according to 1 Corinthians 8:6, is the Father. The "one Lord" in this verse is stated in this book to be under the "one God" (1 Corinthians 11:3).
Consider this verse in terms of the Ignatius Commentary's reading:
1 Corinthians 11:3
3 But I would have you know, that the head of every man is Christ; and the head of the woman is the man; and the head of Christ is God.
Under this reading, the above would be stating that "the head of Yahweh is God". This is one of many examples which could be given in this book, and in the rest of the New Testament, which demonstrate that asserting any kind of identification of Jesus with Yahweh by this author (the Apostle Paul) is just reading confusion into his works. The Apostle Paul very clearly distinguishes God and Jesus, and places Jesus under God.
In summary, the single subject of the Shema, the one God, Yahweh, is the same "one God" of 1 Corinthians 8:6, and is identified as "the Father". The "one Lord" in 1 Corinthians 8:6 is God's exalted Messiah, who has been exalted to Lordship by God (Acts 2:36, Philippians 2:9-11, etc.). Rather than being "one of the clearest Pauline passages to assert both the deity and divine activity of Jesus Christ", this passage has long been a favorite Unitarian proof text, because it so clearly distinguishes between the "one God" and Jesus Christ.