In many ways, religious practice has harmed the both economic and social development of a country and people. The fastest development and greatest progress in the last century was made by communist countries like China and Russia, where the leadership did not promote any religion and was largely atheist or agnostic. Even today, the countries with the highest per capita income like the Scandinavian nations are those where the people are least religious.
In countries like India, religion has been used to discriminate against a person on the basis of both caste and gender for hundreds of centuries. Millions of baby girls are killed even before they are born and they face a lot of discrimination as they grow up. People from lower castes are considered untouchable and denied access to a large number of facilities.
Most religion has no scientific or rational basis, but are often the cause of suffering and death for millions of people due to blind faith. Though some religions are less harmful as they are more tolerant and less racist, they still have their disadvantages and can be manipulated by vested interests.