Now that I have some time I would like to add a few more notes...
The Church is the new Israel, the new Ark of Noah, and Christ is the new Adam; in the new Israel, all can know God. This is why St. Paul teaches "There is neither Jew nor Greek...for ye are all one in Christ Jesus". (Gal. 3:28)
He also wrote: “...For they are not all Israel, which are of Israel. Neither, because they are the seed of Abraham, are they all children... That is, they which are the children of the flesh, these are not the children of God; but the children of the promise are counted for the seed.” This means that genetic ancestery has nothing to do with the new Israel.
Now with regard to your encounter with “replacement theology”, might I point out that the new-calendar “authority” on Church tradition, Kallistos Ware, has succeeded in providing an ample specimen. He attacks the Holy Fathers on some very key conclusions regarding the old Israel, which is summarized above. He is simply the most spectacular circus act on wheels demonstrating how to twist the tradition of the Church while appearing to maintain it, and all for the obviously apparent reason of appealing to modern “ecumenical” efforts and modern sensitivities.