The apostle dealt first with the importance of not judging one another. This was a particular temptation to those Christians who believed that they should refrain from some practices that they believed were displeasing to God but which other Christians felt were legitimate. When Paul wrote, the first group included Jewish Christians who, because of their background in Judaism, tended to perpetuate the practices commanded in the Mosaic Code. Some Jewish Christians do this today as well. In our day this group also includes Christians, both Jewish and Gentile, who for one reason or another do not believe certain amoral (non-moral) practices are proper for a believer even though other Christians judge them permissible. [source][source][source]
An amoral practice is neither right nor wrong in itself. It does not involve sin and, therefore, morality. Examples include food, drink, recreation, clothing, personal grooming, birth control, schooling, lifestyles, et al, when no sin is involved. Some Christians who have black or white mentalities have difficulty recognizing the existence of amoral activity; to them everything is either right or wrong. However, the Bible teaches that there are many activities that may be right but are unadvisable for any number of reasons. Also, there are actions that are right for some people but not right for others. [source][source][source]
"This paragraph divides into three sections: Romans 14:1-12. The divisions between the sections are marked with similar rhetorical questions, each using the second person singular: "Who are you who is judging the servant of another?" ( Romans 14:4 a); "Why are you judging your brother?" ( Romans 14:10 a).... The first ( Romans 14:1-3) and the third ( Romans 14:10-12) state in almost identical language the main point of the paragraph: the "strong" are not to "despise" the "weak"; the "weak" are not to "judge" the "strong" (cf. Romans 14:3 a and10a). In the central section, Romans 14:4-9, Paul provides the theological foundation for these commands: every Christian is a servant of the Lord; and it is to that "master," and not to any other fellow servant, that the believer must answer." [1][source]