Paul writes about walking in love (Romans 14:15) because there were different opinions in the church about some matters. There were two groups, called the weak
and the strong.
He tells the church to act like Christ in this matter (Romans 15:2–3; also see Philippians 2:1–11).
The differences in the church arose from different maturity of faith. The point was how to handle the things that reminded you of your Jewish or pagan past. There was a discussion about (1) eating meat, (2) keeping certain days, and (3) drinking wine.
It is important to note that these are matters of indifference whether (as here) they were customs and ceremonies, or secondary beliefs which are not part of the gospel or the creed
1 that are not clearly stated in the Bible.
1 As for the one who is weak in faith, welcome him, but not to quarrel over opinions.