The Bible says that the Messiah is the root of the olive tree, in which branches (congregation) get spiritual growth. In OT and NT olive tree is a parable about the congregation of God. The Bible says in OT that Israel is a green olive tree, fair, and of goodly fruit. In the New Covenant is also same teaching that he who put his trust in the grace of God in the Messiah is like a green olive tree.

Jer 11:16 The LORD called thy name, A green olive tree, fair, and of goodly fruit: with the noise of a great tumult he hath kindled fire upon it, and the branches of it are broken.

Ps 52:8 But I am like a green olive tree in the house of God: I trust in the mercy of God for ever and ever.