Many people have necklaces, amulets and trinkets in the shape of a 6 pointed star known as "Magen David", the shield of David. There are various sources for this and traditionally it is said to have adorned the actual shield of King David's soldiers as they went to battle. The 6 points symbolize Hashem's presence in all the directions; up, down, front, back, right and left. There is also something called "Magen Avraham", shield of Avraham, as we find in the first beracha of the Amidah. There is no known image or symbol for this, yet it is so vital that it is the first blessing we say in our prayer.
The Imrei Emet of Ger explained that Hashem protects a small particle of Avraham Avinu in every Jew. Deep within the Jewish soul, in our very DNA, is a certain "Avraham chromosome" that carries the gene of inherent emunah as well as a desire to do chessed. Some Jews may ignore it and try to cover it up. A "kofer", non-believer, really means to conceal, to hide or submerge his belief, but the emunah is there, deep deep below. This is the "shielded gene of Avraham" that we commemorate by saying Magen Avraham.
But there is another explanation. "Magen Avraham" refers to the end of days, before Moshiach comes, when the world will be in great upheaval. Two merits will protect us and guard us from harm. 1) learning Torah 2) doing chessed - kindness with each other. Hashem will "shield and protect" (Magen) those who exemplify the trait of "Avraham", namely chessed.
In these trying times, when the Jewish people worldwide are seeing a frightening resurgence of antisemitism, and the Jews in Israel are under attack, let's utilize the merits of Torah and chessed as a protection, by embracing the shield of Avraham.