Why do Christians constantly criticize other Christians?

[Esther]

we are humans and we have the tendency to judge people although it si written in the Holy Bible that "thou shall not judge" we still do ,often without being aware it.its not about what religion/faith you belong to,within every religion be it Christianity,Islam,Judaism people's way of practicing that religion will be different,hence there might be disagreement of certain topic within that faith and ways of dealing with it,so people don't judge for judging sake they just offer their opinion which might come across as judgmental.
Christians don't constantly judge themselves,sometime we know the true but choose to over look it but in the end we come back to our senses.
I don't thin Facebook is the right setting to be reading about Christianity.