Romans 6:17-18 : But thanks be to God, that, whereas ye were servants of sin, ye became obedient from the heart to that form of teaching whereunto ye were de-livered; and being made free from sin, ye became servants of righteousness. The King James Version: "But God be thanked, that ye were servants of sin, but ye have obeyed," etc. Paul did not thank God for the fact that they had been sinners, but for the fact that the sinful part of their lives was a thing of the past. They had been servants of sin, but were not now; they had been delivered from sin. When they became free from sin, they became servants of righteousness; and they became free from sin by obeying from .the heart the form, pattern, or mold, of doctrine into which they had been delivered. James Macknight makes this comment: "The original word tupos, among other things, signifies a mold into which melted metals are poured to receive the form of the mold. The apostle represents the gospel doctrine as a mold, into which the Romans were put by their baptism, in order to their being fashioned anew. And he thanks God that from the heart--that is, most willingly and sincerely --they yielded to the forming efficacy of that mold of doctrine, and were made new men, both in principle and practice." The mold of doctrine is something to which they had already become obedient, and by that obedience had been delivered from the slavery of sin and had become the slaves of righteousness. In other words, by this obedience they had changed masters. It was not simply an inner condition of the heart that had made this change, but obedience that came from the heart. That obedience is spoken of in Romans 6:3-6. The death, burial, and resurrection is the fundamental doctrine. In his death he was buried, and then arose from the dead. In our death to sin we are buried with him, and then are raised up to a new life. The thing that caused Paul to be thankful to God was the fact that, in their obedience from the heart to this mold of doctrine, they had been made free from the slavery of sin and had become slaves of righteousness.