John 15:22 is a scripture verse that seems to point to invincible ignorance. Do you agree?
No it doesnt. At least not in the sense you seem to imply. The Greek word used in that verse means that they didnt acknowledge or consider their sin until Jesus pointed it out. It in no way says they did not have sin until then. That is why we must proclaim the gospel to all. We need to point out that they are lost already unless they turn to Jesus.
The claim by the RCC that those who through no fault of their own do not know Christ are saved is nonsense. If that were true it would be cruel to proclaim the gospel to them. If they were saved in their ignorance but we proclaimed the gospel to them and they didnt believe they would then be lost. If they were already saved why risk their salvation should they not then believe?