Translation
yet to us [there is] one THEOS, the Father, out of whom [are] all things, and we [exist] unto Him, and [there is] one Lord, JESUS CHRIST, by whom [are] all things, and we [exist] through Him. (See comment below.)
Paraphrase
but in contrast to those ideologies, we hold that there is on one CREATOR AND OWNER OF ALL THINGS, also referred to as “God the Father,” who gave all things their existence and we exist for His glory, and there is only one Lord, YHVH’S SAVIOR who is also THE ANOINTED MESSIAH, by whom all things came into being, and we exist because of Him.
ONLY ONE GOD AND ONLY ONE LORD
“To us” is intended as a contrast between what we believe and what the other religions teach. Michael Heiser uses those to words to argue that God is only the one true God in our eyes, but not in real fact because, in Heiser’s mind, other gods do exist. But remember that verse four sets the stage by declaring the guiding principle for this passage – “there is no God except one”.
After the statement that, for us, there is only one God, and after the statement that there is only one Lord, Paul gave indications of why those statements are true, i.e. that God created all things, and that the Lord Jesus Christ was the means of that creation. The Creator is that owner of what He created.