17 For the kingdom of God is not a matter of eating and drinking but of righteousness and peace and joy in the Holy Spirit.
18 Whoever thus serves Christ is acceptable to God and approved by men.
19 So then let us pursue what makes for peace and for mutual upbuilding.
The “strong” believers in Rome valued their freedom to eat and drink what they pleased. Although they rightly understood that the gospel freed them from the need to observe Old Testament ceremonial laws, they had forgotten some more important things. As servants of Christ, they belong to the kingdom of God, and eating and drinking are way down the list of things that have value in that kingdom.
The strong were guilty of the same thing the Pharisees were, only in reverse, as Douglas Moo points out. Whereas the Pharisees valued law over “justice, mercy, and faith” (Matthew 23:23), the strong valued liberty over “righteousness and peace and joy in the Holy Spirit.” In both cases, concern for material things led to neglect of spiritual matters.
Righteousness. This word has two meanings, right standing before God and ethical behavior in relationship with other people. Although the context of this chapter is the second, horizontal meaning, Paul may intend both meanings just as in the next verse he speaks of acceptance before God and approval by men.
Peace. As with righteousness, this word can mean peace with God or with other people, and again Paul could intend both. Peace with God makes possible peace in human relationships, and verse 19 is clearly an exhortation to pursue peace with one another.
Joy in the Holy Spirit. Like peace, joy is a fruit of the Spirit who imparts these qualities to the spiritual community of the church. Nothing drains joy from the church more than when some people appoint themselves to monitor the behavior of others. We are most joyful when our hearts look to the beauty of the Lord in worship.
Colin Kruse well sums up what I think Paul means with regard to these three kingdom qualities:
One’s righteous standing before God must express itself in righteous behavior towards one’s fellow believers; the peace the believer enjoys with God must express itself in peaceful relations with other believers; and joy in the Holy Spirit should promote joyful interaction between believers.
When we live out these principles of the kingdom of God, we serve Christ and his interests and thus do what is acceptable to God. And when others observe the members of the body of Christ living righteously, peacefully, and joyfully with one another, they lend their approval. Instead of the gospel being spoken of as evil, as in verse 16, people now esteem the gospel because of its obvious good fruit.
Harmony and mutual edification in the church are a magnificent witness to all who look on. We recall the Lord’s prayer “that they may all be one, just as you, Father, are in me, and I in you, that they also may be in us, so that the world may believe that you have sent me” (John 17:21).