Is there salvation outside of Jesus Christ?
Intro
Short answer, No.
(Acts 4:10-12 [KJV])
[10] Be it known unto you all, and to all the people of Israel, that by the name of Jesus Christ of Nazareth, whom ye crucified, whom God raised from the dead, even by him doth this man stand here before you whole.
[11] This is the stone which was set at nought of you builders, which is become the head of the corner.
[12] Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved.
There is no salvation in any other name than Jesus Christ, but things will happen in the last days.
(Romans 11:25-26 [KJV])
[25] For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in.
[26] And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob:
Now who are all Israel. I believe that the people that are today called the ethnic Jews are just the tribe of Judah and Levi. So there are 10 more tribes that are Israel. Who are these ten tribes. It is possible that they and ethnic Jews living outside of Israel are going to return to greater Israel in the end times. This could be in the Second exodus.
Ezekiel 20:34 KJV
[34] And I will bring you out from the people, and will gather you out of the countries wherein ye are scattered, with a mighty hand, and with a stretched out arm, and with fury poured out.
So it is possible that there will be a great battle and after that Greater Israel will be formed and then there will be a Second exodus and Jews, the lost ten tribes and believers in the Lord Jesus Christ will return to greater Israel and then the beast system will be on the nations but not on greater Israel.
So there might be a lot of people that will seem to be lost and not believers in the lord Jesus Christ that will eventually be saved.
(Zechariah 12:10 [KJV]) And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and they shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn.
Zechariah 12:10 above is the event the sign of the son of man. In this event believers will be changed but also probably a lot of Jews will be saved here. So it seems that when the fullness of the gentiles be come in a lot of Jews will be saved, probably even Jews who have died will be saved through the event of the dry bones. But they will be saved by seeing Jesus in the sky. So there is no salvation outside of Jesus Christ.
(John 6:40 [KJV]) And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.