Romans 14:19

The things that make for peace in the context refer to practices that do not cause others to stumble and attitudes that are non-judgmental. Peace between the strong and the weak is in view primarily. Rather than tearing down, we should do things that build one another up (1 Corinthians 10:23; 1 Thessalonians 5:11). For the strong this might be foregoing some legitimate amoral practice. For the weak it could be refraining from verbal criticism and judgmental thinking.