The religious seem to justify discrimination. As we all discriminate, because we must make judgments, what is wrong about discriminating amongst religious traditions? Because traditions all seek to understand God within their cultural reference points, we differ as to how we understand reality, God and humans. While humans seek to understand God, as the majority of humans are religious, we should not use God to discriminate.
Discrimination can be along doctrinal lines, where one must adhere to certain beliefs that are and have been traditionally held. These discriminations are the heresy trials, and witch hunts of our country's early Founding. These are understanding of what formulate the creeds. This is the "standards" of belief systems.
Discrimination can also be because one doesn't interpret a text in the right way. Infants must be baptized,; communion must be taken; children must be circumcised; one must cross their hands wile praying; these all are emphasis of undestanding tradition's texts and a reverance for God. What the sacraments mean vary according to the speicific religion and sect.
Some adhere to a wholesale theological framework, in which all of life is understood. These traditions are static and specified in such detail that if one deters from what is orthodox, one has erred and is labelled an infidel.
Discrimination is justified, becasue it affirms our own way of being and undestanding the world. We love to use God for our own purposes. God gives us a sense of power and control; a sense of purpose and a value. Our egos need God's sanction, so we form our "ingroups and our outgroups' based on these understandings and factors.
I truly understand the need to belong. It is one of the most basic of human needs. Humans need support, encouragment and companionship. Of course, some need these blessings more than others.
Justifying our belief systems and our standards of behavior is a rational activity. There is nothing wrong about this either, as all human do this consciously or unconscously. But, when we use our rational resources to maintain an 'in group" at the costs of another, we have stepped past the line for common decency and civil discourse. In our society, discrimination is about belonging to the civil discourse, and there is no justification for discrimination.