Racial characteristics are inherent and unchangeable. Religious beliefs are beliefs, they are subject to debate, discussion and conversion. There is a massive difference between insulting a person's in-born characteristics and questioning or criticising their beliefs.
The crime of Incitement to Religious Hatred was created to close a loophole in the previous law. The crime of Incitement to Racial Hatred already protected Jewish and Hindu people from hate-speech (being both races and religions) so the BNP decided to change their tactics to attacking Muslims (because Islam isn't a race and so they could get away with it).
As with the old adage, exceptions make bad law. The idea of this massive legal apparatus just to stop a BNP hate campaign that few will listen to is ill thought through. As a result of badly-drafted law, it is now illegal to criticise another's religious beliefs too strongly. Religion, unlike race, is based on belief, and is not merely a tribal affiliation – people should have the freedom to discuss the basis of their beliefs freely without fear, in order for religious groups to remain grounded in reason and avoid fundamentalism.
I propose that the crime of Incitement to Religious Hatred be abolished, and the crime of Incitement to Racial Hatred amended to cover not only those groups that are a 'race' by ethnicity, but also any group that views itself as connected by a filial bond in its' belief system (such as Christians, who see themselves as the adopted family of God, or Muslims, who see themselves as the spiritual descendents of Ishmael – this would also cover hatred against other groups like the Freemasons, who see themselves as brothers, or Americans, who are not a single race, but have a common affinity through their constitution and its values). This would mean it would still be a crime to incite hatred against Muslims just for being Muslims, but it would not be a crime to suggest that the belief in polygamy is a degrading idea to women.