Romans 10:20-21 — But Isaiah is very bold, and saith, I was found of them that sought me not; I was made manifest unto them that asked not after me.
But to Israel he saith, All day long I have stretched forth my hands unto a disobedient and gainsaying people.
Verse 20 — Isaiah 65:1 — I am sought of them that asked not for me; I am found of them that sought me not: I said, Behold me, behold me, unto a nation that was not called by my name.
Isaiah is very bold. He prophesied at the risk of his life.
"to Israel" — should be "with reference to Israel"
Verse 21 — Isaiah 65:2 — I have spread out my hands all the day unto a rebellious people, which walketh in a way that was not good, after their own thoughts.
disobedient — refuse to be persuaded
God was patient and entreated Israel, and they heard and understood, but responded with willful ignorance.
all day long — the dispensation of Law
The four "buts" (vs. 18, 19, 20, 21) are for answers to Israel's possible objections
Isaiah 65:1-2 is referring to Israel, so Romans 10:21-22 must also be referring to Israel and to to Gentiles.
The last part of Isaiah 65:1 refers to Jewish leaders who crucified Christ.