How do we know God's grace is for Gentiles?

In the context of Jonah's mission to Nineveh, we see clear evidence that God's grace is not confined solely to the Jewish people but is available to all humanity, including Gentiles. The Old Testament prophets spoke about God's plan to include the Gentiles in His redemptive plan, often highlighting that those who were once considered enemies could be embraced by His mercy. Paul articulates this in Ephesians 3 when he refers to the mystery of Christ, indicating that Gentiles are fellow heirs in the promises of God. This inclusion is a significant theme in scripture, confirming that Christ's death and resurrection opened a pathway for salvation for all who believe, not just the Jewish nation.