Is it wrong to wear a necklace of a magen david (star of David)? Would that be idolatry? And what if I kiss it? Will it then be idolatry?
Rav Ari Enkin describes
From the days of the Arizal, people had the custom of making and wearing amulets with a Magen David. It was recommended that pregnant women wear a Magen David as a segula for an easy childbirth. There are also those who contend that the Magen David was actually the seal of King Solomon which he used in order to control demons,[Gittin 68a] though there is little support for this theory. Yet others argue that the roots of the six pointed star originate from the book of Isaiah where the six aspects of God’s spirit are described.[Yeshayahu 11:2]
It would seem that wearing a Magen Dovid wouldn't pose an issue of avoda zara.