Yes, that is true. They are in Gehenna, the judgment of God which occurred in 70AD.
Luke 19:43-45
“For the days will come upon you when your enemies will throw up a barricade against you, and surround you and hem you in on every side, and they will level you to the ground and your children within you, and they will not leave in you one stone upon another, because you did not recognize the time of your visitation.”
Mark 9:43
"If your hand causes you to sin, cut it off. It is better for you to enter life maimed than with two hands to go into Gehenna, where the fire never goes out. And if your foot causes you to sin, cut it off. It is better for you to enter life crippled than to have two feet and be thrown into Gehenna.
Jeremiah 19:5-7
They have built the high places of Baal to burn their sons in the fire as offerings to foreign gods and false idols—something I did not command or mention, nor did it enter my mind. So beware, the days are coming, declares the LORD, when people will no longer call this place Topheth or the Valley of Ben Hinnom, but the Valley of Slaughter (Gehenna)."
'In this place I will ruin the plans of Judah and Jerusalem. I will make them fall by the sword before their enemies, at the hands of those who seek their lives, and I will give their carcasses as food to the birds of the air and the beasts of the earth.
Gehenna is a physical valley which literally was filled with bodies of those who stayed in Jerusalem when Rome attacked in 70AD and destroyed the Temple. This prophesy was literally fulfilled, and God is no respecter of persons, the religion of Christianity has become like the apostate Judah and the calloused Jerusalem.
Romans 11:13
I am talking to you Gentiles. Inasmuch as I am the apostle to the Gentiles, I make much of my ministry in the hope that I may somehow arouse my own people to envy and save some of them. For if their rejection is the reconciliation of the world, what will their acceptance be but life from the dead? If the part of the dough offered as firstfruits is holy, then the whole batch is holy; if the root is holy, so are the branches.
If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root, do not boast over those branches. If you do, consider this: You do not support the root, but the root supports you. You will say then, “Branches were broken off so that I could be grafted in.” Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but be afraid. For if God did not spare the natural branches, he will not spare you either.
Consider therefore the kindness and sternness of God: sternness to those who fell, but kindness to you, provided that you continue in his kindness. Otherwise, you also will be cut off. And if they do not persist in unbelief, they will be grafted in, for God is able to graft them in again. After all, if you were cut out of an olive tree that is wild by nature, and contrary to nature were grafted into a cultivated olive tree, how much more readily will these, the natural branches, be grafted into their own olive tree!
That which happened to Israel was physical destruction, but as prophesy is being fulfilled, Israel is being grafted back in because we, as gentiles, have gone astray concerning God and His promises. Gehenna is a warning, but it is not a permanent end, it is a sign to the generations.