The Catholic Church's position on Israel's right to the Land has always been grey at best, while the Bible is black and white. Consider these biblical facts:
• The Land belongs to the creator (Lev. 25:23)
• The Land was given by the creator to the descendants of Abraham (Gen. 12:7)
• The Land was given unconditionally through a Covenant (Gen. 17:7-8)
• The Land was given by the creator to the descendants of Isaac (Gen. 17:19)
• The Land was given by the creator to the descendants of Jacob (Gen. 28)
• The Land promise is as certain as the order of the universe (Jer. 31:35-37)
• The Land's name is Israel not Palestine (Eze. 37:11-12)
• The Land will see real peace only when the Messiah returns (Eze 39:25-29)
In recent years, we have seen some efforts from the Catholic Church in trying to mend the relations between Catholics and Jews.
One thing needs to be clear though, some Catholics are followers of Messiah Yeshua (Jesus) or "Christians" as we may say, but not all Catholics have a personal relationship with the Creator through the death and resurrection of His Son Yeshua.
Catholic Replacement Theology claiming that God's promises to Israel are now directly given to the Church is prevalent, yet we shouldn't see it as "all Christians being antisemitic".
This being said, this recent decision from the Catholic Church to officially announce Israel's rejection by the creator, is far from a step in the right direction. For more on this, please read a great article from "Arutz Sheva" (link to article).