But God be thanked - The argument in this verse is drawn from a direct appeal to the feelings of the Roman Christians themselves. From their experience, Paul was able to draw a demonstration to his purpose, and this was with him a ground of gratitude to God.
That ye were ... - The sense of this passage is plain. The ground Of the thanksgiving was not that they had been the slaves of sin; but it is, that notwithstanding this, or although they had been thus, yet that they were now obedient. To give thanks to God that people were sinners, would contradict the whole spirit of this argument, and of the Bible. But to give thanks that although people had been sinners, yet that now they had become obedient; that is, that great sinners had become converted, is in entire accordance with the spirit of the Bible, and with propriety. The word “although” or “whereas,” understood here, expresses the sense, “But thanks unto God, that whereas ye were the servants of sin,” etc. Christians should thank God that they themselves, though once great sinners, have become converted; and when others who are great sinners are converted, they should praise him.
The servants of sin - This is a strong expression implying that they had been in bondage to sin; that they had been completely its slaves.
From the heart - Not in external form only; but as a cordial, sincere, and entire service. No other obedience is genuine.
That form of doctrine - Greek, type; see the note at Romans 5:14. The form or type of doctrine means that shape or model of instruction which was communicated. It does not differ materially from the doctrine itself, “you have obeyed that doctrine,” etc. You have yielded obedience to the instructions, the rules, the tenor of the Christian revelation. The word “doctrine” does not refer to an abstract dogma, but means instruction, that which is taught. And the meaning of the whole expression is simply, that they had yielded a cheerful and hearty obedience to what had been communicated to them by the teachers of the Christian religion; compare Romans 1:8.
Which was delivered you - Margin, “Whereto ye were delivered.” This is a literal translation of the Greek; and the sense is simply in which you have been instructed.