The use of the word "slave" in English translations of Romans is quite unfortunate because it can be used to imply something which isn't there. The word in question is douloV which really means a bondsman or a type of bound house servant not a field or quarry slave. The KJV translates it as "bondsman" and that's pretty close. In the first instance Harley cited we are servants in the house of the Evil One, in the second, in the House of the Lord.
I think you will find that hesychastic fathers leave no doubt that we are born in complete depravity, slaves to sin (oh yeah, the Calvinists would love that part!), unable to choose anything but evil, and that we are saved by God's loving grace out of that rot.
I am no expert on Greek of course, but is it correct that the ancient Greek term for "slave" became the modern Greek word for "laborer" or "bondsman?" Ancient Greeks considered every man who worked for someone else not feee. Only those who worked for themsleves were considered free men. Anyone serving anyone else was not.
If man is bonded one way or another, man is never truly free. Yet Scriputre tells us just the opposite: unlike the animals, who are driven by necessity and are bonded to necessity, we are free to choose. Adam and Eve were free to choose not only God but evil, thus being totally and truly free.
If we were bonded to God, then we would do nothing that He doesn't want us to do, we couldn't sin. The error of Protestants is precisely their claim that once they accept Christ they cannot sin. And they have issues with the church or Papal infallibility?