Part of the great diversity of humankind is the many different religions and belief systems we have developed – Animism, Buddhism, Christianity, Hinduism, Islam, Jainism, Taoism, and many more. Religious beliefs have a strong influence on the culture of a community.
Religion defines how the community members interpret their role in the universe, with this teaching based on the local culture, so different religions rise out of different cultures. Similarly when members of one religion convert members of a foreign culture often the resulting religion in that area is affected by the host culture.
According to the book by Jonathan Haidt, the Righteous Mind, most of humanity seems to fall into valuing one of two tendencies higher than the other, either tolerance or loyalty and conformance. I suspect those valuing conformance higher than tolerance can be influenced into intolerant behaviors. This book also points out the inherent groupish nature of people. These tendencies provide the foundation for the typically divisive political leadership of today.