Without knowing Jesus, without accepting Jesus as Savior, and without the indwelling Holy Spirit who lives in every believer, nobody can enter heaven.
How were Old Testament Saints saved? By Faith in God and faith in the coming Messiah Jesus.
Jesus is the God of all creations. He is the Messiah for whom the Jews eagerly awaited. He fulfilled all the old testament prophecies about Him, except those related to His second coming and future events.
The Gospel is the same for Jews and Gentiles. Whoever believes in the One True Triune God (God- The Father, God- The Spirit, God- The Son) and accepts Christ as their Savior, believing in Him ALONE(NOT self-righteousness, NOT Church, NOT Baptism, NOT Sacraments, NOT Religion, NOT Mary or Saints) for Salvation, shall be Saved.
Romans 10:12 - "For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him."
JESUS IS THE MESSIAH. NO ONE WHO DENIES HIM CAN GO TO THE FATHER
God is the creator of the universe, heaven, earth and all living things. He created every living creature and finally created Man in His very image. God gave man authority over all other creations. While every creature served and lived the purpose for which God created them, man did not. Man disobeyed God and sinned.
Every human being is a sinner and deserves eternal punishment in hell.
No human being ever lived a perfect life, nor will anyone achieve sinless perfection in future in this life. Also, we inherit sin from Adam. The only exception to this is the God-man Jesus.
But, God desires that we all should escape the everlasting hell that we deserve. However, He has to punish sin because He is a just God. That is why Christ had to die on the cross, pay for our sins and buy our pardon.
Salvation is a gift of grace, available to everyone who believes in the Only True Living God(Father, Spirit, Son) and Christ's Sacrifice ALONE(Not Religion, Not Self-Righteousness, Not Mary, Not Saints, Not Sacraments etc.) for Salvation.
John 3:16 - For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
Romans 6:23 - "For the wages of sin [is] death; but the gift of God [is] eternal life through Jesus Christ our Lord."Jesus is the ONLY WAY to Heaven
This Post: Are all Jews Saved?
Other posts you may be interested in:How to go to Heaven?