Is taking money from a store without the owner's knowledge and then returning it without his knowledge considered theft?

It is not permissible to take money from a shop without the owner's permission, even if you intend to return it. This is because the shop owner has entrusted you, and the Prophet, peace and blessings be upon him, said: "Render the trusts to those who have entrusted you, and do not betray those who betray you," and "The wealth of a Muslim person is not lawful except with his willing consent."