Why is the Star of David Christian? The answer is very simple: Jesus was of the House of David.
Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God, which he had promised before, by his prophets, in the holy scriptures, concerning his Son, who was made to him of the seed of David, according to the flesh.
2 Timothy 2:8:
Be mindful that the Lord Jesus Christ is risen again from the dead, of the seed of David, according to my gospel.
Regardless of the difficulties presented by the two genealogies in the Gospels, the above two quotes make it clear, and scripture cannot lie (cf. John 10:35), that Jesus is of the seed of David according to the flesh.
Since his flesh was of the Blessed Virgin, she must have been of that House.
"Tradition tells us that Mary too was a descendant of David. According to Numbers 36:6-12, an only daughter had to marry within her own family so as to secure the right of inheritance. After St. Justin (Adv. Tryph. 100) and St. Ignatius (Letter to the Ephesians 18), the Fathers generally agree in maintaining Mary's Davidic descent, whether they knew this from an oral tradition or inferred it from Scripture, e.g. Romans 1:3; 2 Timothy 2:8."
That the six-pointed star should not be considered strictly a Jewish symbol has been underscored by a recent controversy involving (who else?) Donald Trump.
Certain people, with questionable motives, have accused Mr. Trump, who has three Jewish grandchildren, of using anti-Semitic imagery in the above Tweet, since the six-pointed star has been appropriated in popular culture as being exclusively a Jewish symbol, which should not be the case. Trump simply wanted to highlight "most corrupt candidate ever" within a star, any star, and this one just happened to have six points.
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