Romans 14:17 is saying that the Kingdom of God is not a matter of what we eat or drink, but of living a life of goodness and peace and joy in the Holy Spirit.

The Kingdom of God is a matter of living a life in the Holy Spirit. It is not a matter of eating or drinking. The Kingdom of God is all about something much more important than food. It is more important than any human interests or activities. The Kingdom of God is all about a righteous life, a peaceful life, and a joyful life – produced by the Holy Spirit.