Britney wrote this song with Sia. The Australian singer-songwriter also co-penned "Perfume" and "Passenger" for Britney Jean.
The song is addressed to Jesus, who described himself in Revelation 22:16 as THE bright Morning Star. Christ is also called the Morning Star in Revelation 2 :28 and 2 Peter 1:19. Britney sings:
"You're my light when it gets dark You will always in my heart You're my brightest morning star"
A morning star appears just before dawn, when the night is at its darkest. The idea of the 'brightest morning star' is one that outshines all the others. Jesus is the most holy and powerful "light" in all the universe and He promises in the Bible that when everything seems at its bleakest point, His light will shine in the darkness providing protection and guidance.