13. What is represented by (a) the olive tree, (b) its root, (c) its trunk, and (d) its branches?

¹³ The apostle Paul goes on to compare those who become part of Abraham’s seed to branches on a symbolic olive tree.a (Rom. 11:21)

The branches collectively represent “the full number” of those included in the secondary part of Abraham’s seed.

14, 15. Who were “broken off” the cultivated olive tree, and who were grafted onto it?

¹⁴ In the illustration of the olive tree, the natural Jews who rejected Jesus are likened to olive branches that were “broken off.” (Rom. 11:17) They thereby lost the opportunity to become part of Abraham’s seed. But who would replace them? From the standpoint of the natural Jews, who prided themselves on their fleshly descent from Abraham, the answer would be unthinkable. But John the Baptizer had already forewarned them that if Jehovah wished to do so, he could raise up children to Abraham from the very stones.​—Luke 3:8.

¹⁵ What, then, did Jehovah do to fulfill his purpose? Paul explains that branches from a wild olive tree were grafted onto the cultivated olive tree to replace those broken off. (Read Romans 11:17, 18.) Thus, spirit-anointed Christians of the nations, such as some in the congregation in Rome, were figuratively grafted onto this symbolic olive tree. In this way they became part of Abraham’s seed. Originally, they were like wild olive branches, not having any opportunity to be a part of this special covenant. But Jehovah opened the way for them to become spiritual Jews.​—Rom. 2:28, 29.