Were the Old Testament saints limited only to the Israelites according to the Bible or were any gentile nations included in the contract with God?
When you say contract, you are probably referring to the covenant. The covenant itself was only for Israel. It was Israel that God was making not only a nation, but also his nation. So they are the only ones to have received the covenant at Mount Sinai with Moses.
However, throughout the Old Testament there are signs that other people from the nations, Gentiles, came to become believers in God. Yahweh may have taken Israel as his own nation, but he also meant for them to evangelize nations around them.
For instance, take Jonah. He goes to Nineveh for the express purpose of telling them that God’s judgment is coming their way. Nineveh was the capital of Assyria, at the time, Israel’s enemy. Cereal was the nation to take the northern kingdom of Israel into exile.
Jonah was no friend of the Ninevites. When he went to Nineveh to proclaim God’s judgment, he almost relished telling them that God was going to destroy them in his wrath. However, as is always the case with God’s judgment, there is always a note of grace.
Jonah was not only required to tell the Ninevites that God was going to judge them and destroy them but that if they would repent he would turn from his judgment and embrace them. The nightmare for Jonah is that the people responded to the message he gave by repentance. God spared his arch enemies, the Ninevites.
Throughout the Old Testament, we read stories here and there of one or two, maybe even an entire family, accepting the message of Israelite prophets who brought the same types of messages as Jonah to Gentiles who received them and changed from their ways.
So while there is probably only the one reference to the Ninevites, a whole city of Assyrians, accepting the message of repentance and responding to it, we see Gentiles coming to God through Israelite evangelism in the Old Testament.
The sad thing is that these are rare occurrences instead of the regular operation of Israel. They tended to look down on the nations around them because the nations did not receive the special revelation of God’s Law.
Israel enjoyed knowing exactly what God expected of them, but the nations around them scratched in the darkness hoping to stumble upon whatever would please their gods. Most of the time, the Gentiles had no idea how to please their idols.
The Israelites could have used this as part of their witness to the nations around them, but sadly most of the time they scoffed at their neighbors. Nobody is perfect and evangelism efforts. We all make these mistakes from time to time.
May the story be told of Christians that they reached out at every opportunity to preach God’s kingdom through words and actions to everyone they met.