There was a comment made recently comparing the State of Israel and True Israel, in reference to the Jews vs the Christians. What the? Oh boy. *facepalm*
Ok, true Israel is the same as the State of Israel. There is no difference. The Israel we know today is the same Israel who came out of Egypt all those years ago. Over many generations they've been dispersed to the far reaches of the earth, and are now being brought back, but they are the same group of people. The Christians did not replace them. There is no 'Old' and 'New', 'Old' and 'True' Israel. There is just Israel. G-d did not set Israel aside and pick up a new group of people instead to be his prize possession. It just doesn't work that way. G-d does not change his mind, so why would he swap one group of people for another? In replacing the Jews with the Christians, you're calling G-d a liar.
It can be understood as a family. A father has 2 sons, his older biological son and his younger adopted son. He loves them both, for they are both his children! The father does not forsake his older son in favor of his younger son, does he? Nor does the adopted son have any right to say to the biological son "Away with you, this is my place". No! The adopted son should be glad to be a part of the family.
Likewise it could be understood as a tree. The roots, trunk, and branches are the Jewish people. There are also other branches grafted in, those are the Christians. Without the roots, the whole tree will die.
Concerning the State of Israel vs true Israel, there is no difference, it is the same. Instead of sibling rivalry, why don't we try some brotherly love? The whole world will benefit from it.