The Islamic Law blog has a post on arguing about faith. Basically what it says is to avoid religious arguments. This is a sound advice and I agree with it because faith comes by understanding and not by arguing.
But sometimes I come across Muslims who take this into the next level and altogether avoid engaging in religious discussions. Maybe this is because they don’t have the knowledge or ability to discuss and explain Islam. Or maybe they don’t have much faith! Or maybe they think that the truth about Islam and reasons for various religious rules is obvious so everyone will see it and assume that there is no need to explain it.
Be it whatever the reason this attitude among some Muslims towards discussing religion is one of the main reasons why there are so many misconceptions about Muslims and why many non-Muslims strongly believe that Muslims are intolerant and fear to talk with Muslims about religion.
So the position of a Muslim should be to avoid arguments but engage in discussing religion.
Misc: When discussing religion or aspects of it, it is important to explain them so that people understand the reasons and benefits of them too.