Is Mehandi a religious custom?
No, it’s a cultural one, crossing the boundaries of religious differences. It is traditionally used at times of celebration to dress up, or any time women got together and wanted to beautify themselves. Suggesting that mehndi is religious to Hindus, Muslims, or Jews, would be like suggesting that nailpolish and eyeliner is religious to Christians. If you choose to have mehndi done, it should not offend anyone’s religious sensibilities.