For when you were slaves of sin, you were free in regard to righteousness. But what fruit were you getting at that time from the things of which you are now ashamed? For the end of those things is death. But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life. For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord (Romans 6.20-23, ESV).

For when you were slaves of sin, you were free in regard to righteousness. Therefore what benefit were you then deriving from the things of which you are now ashamed? For the outcome of those things is death. But now having been freed from sin and enslaved to God, you derive your benefit, resulting in sanctification, and the outcome, eternal life. For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord (Romans 6.20-23, NASB).

For when ye were the servants of sin, ye were free from righteousness. What fruit had ye then in those things whereof ye are now ashamed? for the end of those things is death. But now being made free from sin, and become servants to God, ye have your fruit unto holiness, and the end everlasting life. For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord (Romans 6.20-23, KJV).

For when ye were servants of sin, ye were free of rightwiseness. Therefore what fruit had ye then in those things, in which ye shame now? For the end of them is death. But now ye delivered from sin, and made servants to God, have your fruit into holiness, and the end everlasting life. For the wages of sin is death; the grace of God is everlasting life in Christ Jesus our Lord (Romans 6.20-23, Wyclif).

For when ye were the servants of sin, ye were free from righteousness. What fruit had ye then in those things whereof ye are now ashamed? for the end of those things [is] death. But now being freed from sin, and made servants unto God, ye have your fruit in holiness, and the end, everlasting life. For the wages of sin is death, but the gift of God is eternal life, through Jesus Christ our Lord (Romans 6.20-23, 1599 Geneva).

Westminster Confession, chapter 16, Of Good Works

II. These good works, done in obedience to God’s commandments, are the fruits and evidences of a true and lively faith: and by them believers manifest their thankfulness, strengthen their assurance, edify their brethren, adorn the profession of the Gospel, stop the mouths of the adversaries, and glorify God, whose workmanship they are, created in Christ Jesus thereunto, that, having their fruit unto holiness, they may have the end, eternal life [prooftext: ROM 6:22 But now being made free from sin, and become servants to God, ye have your fruit unto holiness, and the end everlasting life].

To say that good works are a means to eternal life is not a denial that good works are only the result (“fruit” metaphorically speaking) of God’s work of grace in one’s life.  Neither in the Bible nor in the Westminster Standards is it possible to play one concept off against the other as if they were mutually exclusive.