Note 14 at Ro 14:17: People usually focus their attention on external things, such as meat and drink, but God is always concerned with the heart (1Sa 16:7). God deals with people's actions because they indicate the condition of their hearts. However, it is always the spiritual condition of the inner being that God is seeking to change.

Paul was saying that we need to be like God and focus on the inner condition of our brothers and sisters in Christ. Then we will be able to tolerate minor differences in their actions.