Romans 14:17 - The kingdom of God is not a matter of eating and drinking, but of righteousness, peace and joy in the Holy Spirit.
This verse tells us that ceremonial food distinctions are not the signs of the rule of God in the church or the Christian life. Rather, righteousness, peace and joy in the Holy Spirit are the true signs of a God-centred life.
Righteousness in Romans always refers to God's righteousness which he freely gives to one who trusts Christ as Saviour and Lord. That person no longer faces the wrath of God since Christ paid that penalty and rose from the dead.
Peace is peace with God through the Lord Jesus Christ. And it is also the peace of God that passes understanding, when we trust him with our requests.
Joy in the Holy Spirit refers to the only true joy found in life for it is found in Christ.
The Kingdom of God cannot be found in rituals or adherence to man-made rules. The Kingdom of God can only be found in knowing Christ; and that means righteousness, peace and joy in the Holy Spirit.