Presumably, you have an ancestor with the Hebrew name Chaim, which means life, and in the secular world, he or his parents gave him the translated name Vidal. Anyway, given names of parents sometimes become family names of their children and later descendants, and so Vidal became a family name. Vidal as a Jewish name is the translation of the Hebrew Chayim or Hayim. This means life in Hebrew. Being that you are in Belgium, and assuming your ancestors were there for generations, I would assume you have Sephardic heritage.
Life is an important concept in Judaism.
Its ritual and history celebrate life whereas Christianity being focused on death and resurrection have different emphasis. Chayim is a very common name as a result among Jews. Many Sephardim came to the Netherlands and Belgium to escape Inquisition persecution. Some re-converted to Judaism like the Espinosa, da Costa, de Castro's, Pinto's, etc. Your family could have fit into the second category.