There were non Jews saved before Christ. It was always available to all.
For example,
Psalm 2:12, "Blessed are all who take refuge in him." This "refuge" was faith or trust in the Lord. This was not an ambiguous idea of God, but faith in the one God who created the heavens, the earth, and everything in them.
With the coming of Jesus, the content of faith became more specific, growing from belief in God and His ways to acceptance of the Son whom He sent as Savior. The promised Messiah had arrived. Jesus was the fulfillment of the Old Testament sacrificial system, the one Savior who permanently restores relationship with God.
With the completion of the New Testament writings, we now have far more information than previous generations who lived with little knowledge of Jesus. As
Hebrews 1:1-2 says, "Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world." We have all that is necessary to believe in Jesus Christ by grace through faith (
Ephesians 2:8-9).
Prior to Jesus, salvation was based on faith in God and trust in His plan. Ultimately, it was still based on the death and resurrection of Christ, though God's followers did not know exactly how that would look.
The ancient Gentiles were not judged by the same rule as the Jews due to the fact that the Hebrews had a written revelation from God (the law of Moses, and eventually the completed body of the Old Testament Scriptures), while the other nations did not; the Gentiles, therefore, were evaluated by a more general standard than the Jews. Paul wrote:
[F]or when Gentiles that have not the law do by nature the things of the law, these, not having the law, are the law unto themselves; in that they show the work of the law written in their hearts, their conscience bearing witness therewith, and their thoughts one with another accusing or else excusing them in the day when God shall judge the secrets of men, according to my gospel, by Jesus Christ (Romans 2:14-16).
While the Gentiles did not have a written law (e.g., the law of Moses) certainly on occasions they had communications from Jehovah (cf. Genesis 3:9; 4:6; 6:13ff; 12:1ff)
“According to Romans 2:14-15 conscience is innate and universal. It is not the product of environment, training, habit, race impression, or education, though it is influenced by all these factors” (Rehwinkel 1999, 136). The ancient Gentiles, therefore, were not judged by the same rule as the Jews, but they were not void of law and culpability.
The Lord sent Jonah to the Gentiles of Nineveh (Jonah 3:1). God’s mercy and compassion extend even to the heathen nations on condition of their repentance”
Four Gentile women were woven into the genealogical fabric of the Messiah—Tamar, Rahab, Ruth, and Bathsheba—in both legal and biological senses (Matthew 1:5-6; Luke 3:31-32). Non Jews were saved before Christ.