Why do Catholics worship relics of Saints?

The Catholic Answers

They do not worship relics as they worship God, by adoration. If you mean worship in the sense of honor or veneration, then Catholics certainly venerate the relics of Saints. The law, “Honor thy father and thy mother” extends to their persons, body and soul; to their reputations, and to all connected with them. We reverence their remains even after death. And if we are not to venerate the remains and relics of the Saints who have been so entirely consecrated to God, are we to desecrate them? Or are we to be blandly indifferent to them as to the bleached bones of some dead animal lying in the fields? The Catholic doctrine, forbidding adoration, yet commanding respect and veneration, is the only possible Christian conduct.

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty