"Let all the house of Israel know certainly, then, that God makes Him Lord as well as Christ - this Jesus Whom you crucify...Repent and be baptized each of you in the name of Jesus Christ...repent and return, so that your sins may be wiped away, in order that times of refreshing may come from the presence of the Lord; and that He may send Jesus, the Christ appointed for you, whom heaven must receive until the period of restoration of all things about which God spoke by the mouth of His holy prophets from ancient time...It is you who are the sons of the prophets and of the covenant God made with your fathers." (Acts 2:36-39; 3:20-25)
Israel did not repent and blindness came upon Israel that remains to this day. However, one day Israel will repent and be baptized, each of them in the name of Jesus their Messiah, and He will return.
"For I would not, brethren that ye should be ignorant of this mystery, that blindness in part is happened to Israel, until the fullness of the nations be come in. And so all Israel shall be saved: as it is written, There shall come out of Zion the Deliverer, and shall turn away ungodliness from Jacob." (Romans 11:25-26)
Repentance and water baptism is a requirement for the kingdom of Israel to come, and it will last 1,000 years. However, eternal salvation in the Kingdom of God is a free gift from God to all nations.
"For the wages of sin is death, but the free gift of God is eternal life through Christ Jesus our Lord." (Romans 6:23)
The BLOOD of Jesus that took away the sin of the world.
"The next day John saw Jesus coming toward him and said, Look, the Lamb of God, who takes away the sin of the world!" (John 1:29)
"But if we are living in the light, as God is in the light, then we have fellowship with each other, and the blood of Jesus, his Son, cleanses us from all sin." (1 John 1:7)