Romans 6:17-18
(17) But God be thanked, that ye were the servants of sin, but ye have obeyed from the heart that form of doctrine which was delivered you.
(18) Being then made free from sin, ye became the servants of righteousness.
This discussion reminded the Apostle Paul of what the grace of God had already accomplished in his readers’ lives and he burst forth in praise. Before they responded to the gospel they had been slaves to sin, but they wholeheartedly (lit., “out from hearts,” thus inwardly and genuinely, not merely externally) obeyed (cf. “obedience” in 1 Peter 1:2) the form of teaching to which they were entrusted. Hearing the teaching of God’s Word, they committed themselves to those truths. That commitment was evidenced by their response to the gospel and their being baptized. The result was that they have been set free from sin and have become slaves (past tense in Gr.) to righteousness (cf. Rom. 6:22). This is positional and must be manifested in daily experience, but it demonstrates again that there is no middle ground. Christians are not to give in to sin because they are dead to it and no longer slaves of it. It is totally contrary to God’s plan for slaves of righteousness to become enslaved to sin!
Excerpt from:
Walvoord, J. F., Zuck, R. B., & Dallas Theological Seminary. (1983-c1985). The Bible knowledge commentary : An Exposition of the Scriptures. Wheaton, IL: Victor Books.
Below are FB comments on the book of Romans (The Bible Knowledge Commentary):