Let's review what is being said here.
Paul says, "Consequently, faith comes from hearing the message, and the message is heard through the word of Christ."
Then Paul asks, "Did they not hear?"
To this Paul then asserts that they did hear the message through the word of Christ.
And how does Paul say that they heard the message through the word of Christ?
Paul quotes Psalm 19:4 as a proof text as follows, "Their voice has gone out into all the earth, their words to the ends of the world."
In other words, the word of Christ has gone out into all the earth, the words of Christ to the ends of the world -- so there is no excuse for not believing in God just as Paul said before in Romans 1:20
I am pretty sure that this applies only to Israel, to whom God sent many preachers and prophets to give them the "Word of Christ." I am not sure that the natural revelation of "the heavens declare the glory of God" is the same as the "Word of Christ."
If you say there no absolutes, I ask you, are you absolutely sure?