the bride of Christ

What does it mean that the Church is the Bride of Christ?

Revelation 19:6-9

Then I heard what sounded like a great multitude, like the roar of rushing waters and like loud peals of thunder, shouting:

“Hallelujah!
    For our Lord God Almighty reigns.
Let us rejoice and be glad
    and give him glory!
For the wedding of the Lamb has come,
    and his bride has made herself ready.
Fine linen, bright and clean,
    was given her to wear.”

(Fine linen stands for the righteous acts of God’s holy people.)

Then the angel said to me, “Write this: Blessed are those who are invited to the wedding supper of the Lamb!” And he added, “These are the true words of God.”