Dr. Tawde is associated with a division of Sanatan Sanstha, an organization based in Goa that immerses its followers in a regimen of meditation and chanting, offering what it calls an escape from addiction and materialism. The group’s founder, a former hypnotherapist known as His Holiness Dr. Jayant Athavale, has called the shooting “a blessing from God” because Dr. Dabholkar had escaped dying from old age.

Image Dr. Dabholkar, a physician who spent his adult life crusading against spiritual practices he considered fraudulent, was shot to death. Credit... Associated Press

At the time of his murder, Dr. Dabholkar had been lobbying intensively for the passage of legislation banning a list of mystical practices, including animal sacrifice, the magical treatment of snakebites and the sale of magic stones.

He had many enemies, having spent decades trying to weaken the pervasive cultural influence of gurus, godmen and religious activists in India. Among his endeavors was a roadshow in which activists performed what some people called feats of magic, such as lying on a bed of nails, in order to debunk them. They told crowds, “Just remember, miracles can never happen.”

Hamid Dabholkar, Dr. Dabholkar’s son, said that several years ago Dr. Tawde and his father had lived in the same city, where Dr. Tawde led violent protests against his father over the issue of ritual immersions of Hindu idols in rivers and lakes. Dr. Dabholkar opposed that practice, saying it polluted natural water sources.

Later, Mr. Dabholkar said, Dr. Tawde confronted his father over the legislation against black magic. “It indicates that it was cooking for a long time, planned and executed in cold blood,” Mr. Dabholkar said.