Romans 10:18-21 - Jews Rejected, Gentiles Included - The Old Testament Predicted Both

The Old Testament prophets foretold of the universal spread of the Gospel and the inclusion of Gentiles as God's people as well as the rejection of the Gospel by Israel.

  [Having shown that it is necessary for all men to hear the gospel in order to be saved, Paul goes on to point out that the gospel has been preached to all men without distinction]:
10:18 But I ask: Did they not hear? [the gospel]
Of course they did:

"Their voice has gone out into all the earth,
their words to the ends of the world."

[Note: In describing the spread of the gospel in his day, Paul used the language of Psalm 19:4 which teaches that creation testifies to the existence of an all-wise Creator. Just as the unspoken message of creation is available for all men without distinction to observe, so too the gospel in Paul's day was being preached throughout the world to all men without distinction in keeping with the Lord's command (Matthew 28:19). In effect, the unspoken "voice" of the heavens which communicated the work of God in creation to all nations prefigured the voice of God's servants in Paul's day (and ours) which communicated the work of God in salvation to all the nations of the earth.]

[Paul then points out that Israel should have understood from their (Old Testament) Scriptures that there would come a time in history when they would reject God and that God would reveal Himself to other nations instead]:

10:19 Again I ask: Did Israel not understand?
[That they would reject God and God would turn to the Gentiles]?

[They should have! Paul cites two (2) places in the Old Testament where such an event was predicted]:

[1] First, Moses says, [In Deuteronomy 32:21]

"I [God] will make you [Israel] envious
by those who are not a nation
[The Gentiles];
I
[God] will make you [Israel] angry
by a nation that has no understanding
[The Gentiles]."

10:20 [2] And Isaiah boldly says [in Isaiah 65:1],

"I [God] was found by those who did not seek me;
I
[God] revealed myself to those who did not ask for me."

10:21 But concerning Israel He says [in Isaiah 65:2],

"All day long I have held out my hands
to a disobedient and obstinate people."