When we claim that Islam is a comprehensive system that covers every area of life, we have to be aware that we are thereby calling attention to our own behaviour. If we behave badly, this will not be construed as a discrepancy between one individual’s actions and what the religion teaches; it will be assumed to be behaviour commanded or allowed by the religion.
Therefore, be cognizant that your behaviour is always a proof for or against Islam in the minds of those around you. it can either draw people to the Deen or make them doubt it.