Arguments on food to eat exist since ancient times. 'Some believe in eating anything, while the weak eat only vegetables.' Arguments on days to worship exist since ancient times as well. 'Some value this day over that day, while some equalize each of the single day.'
There is no necessity to set mandatory standards on food to eat or days to worship. There is no necessity to force others to obey such standards either. That is due to the fact that 'we worship for the sake of our Lord'; 'we eat for the sake of our Lord'; 'we fast for the sake of our Lord'. Therefore, we should accept others as we have been accepted by the Lord, and judge no one.
Who am I? For who give me the right to judge others' servants? The fact is his Lord will always be with him no matter he stands firm or falls over. It is also true that the Lord making me stand firm has the same power to help him.