This paper investigates the relationship between different religious groups and income inequality. In particular, we examine whether different religious groups (Christianity, Islam, Judaism and Buddhism) have an impact on income inequality in a global perspective. Furthermore, this paper also sheds light on the effects of major religious sub-groups (Christianity and Islam) on income inequality. Using data for 130 countries from 1970 to 2013, we estimate a panel data model, controlling for religious beliefs, savings rate, arable land rate and age-dependency ratio. Our results indicate that religion plays an important role in explaining income inequality. In particular, we found that Islam and Judaism reduce income inequality while in general, Christianity and Buddhism increases inequality. However, the effects from sub-groups of Christianity on inequality are mixed; in particular, Anglican and Orthodox significantly reduce inequality while the effect from Catholic and Protestant is opposite. These findings are robust to different measures of inequality and alternative estimation techniques that take care of endogeneity.