I was interested in 1DAD's mention of Calvinism earlier.
The white settlers in South Africa were profoundly influenced by the doctrine of predestination. They were convinced they were the elect and the blacks were the damned. The apartheid system grew out of the Calvinistic roots of Afrikaner society.
Nowadays people are horrified that such racism was ever tolerated. On the other hand the religious prejudice - ‘religionism’ - in the Bible and later Christian writings that legitimised racism in the minds of the white Afrikaners is an influence to this day in many societies worldwide.
I would like Christians to substitute believer and non-believer/believer in a different religion with white and black at every point in the Bible where a distinction is made and see how it sounds.
It might be argued that - unlike with being black - people can do something about being a non-Christian but I don’t think this is the case. Whether you are religious or not is, in my opinion, an innate trait and the particular way your religiosity is manifest is mainly determined by geography/cultural background.
Many conservative Christians will tell you outright that you are not going to heaven if you are a non-believer. Liberal Christians are more likely to prevaricate and say that they know they are going to heaven and as for you, that’s up to God.
Even the softer statement of the liberal Christian would not be acceptable if it were a white person saying the same thing to a black person. So why is it acceptable for a believer to say it to a non-believer?
Whether or not there is a heaven or not is immaterial, the mere idea of an afterlife that discriminates on religious grounds has a malign influence on society. Sikhism holds the possibility of heaven open to non-Sikhs in its holy writings, so discriminatory afterlives are not a given.
It is my hope that in the future people will be more aware of religionism in their holy books just as they have become more aware of prejudices against gay people and women.