Jesus told the disciples . . . Jews . . . to teach everything He commanded, to
"all the nations", in Matthew 28:19-20, which I understand includes us Gentiles. Jesus started with Jews, but now their cup is running over to us
Paul himself says we have been grafted in with the Jews > Romans 11:16-18. There are branches of Jews who have been broken away from the olive tree, and we Gentiles have been grafted in where certain Jesus-refusing Jews have been broken away. So, we have joined the true Jews who have been circumcised in their hearts > Romans 2:28-29.
So, what do you mean by a "kingdom message" which is no longer for people, now?
Even though we are no longer under the Law, Paul uses the Law, in various epistles, to minister to us who are children of God. And he says all scripture is
"profitable". Our Apostle Paul says this in his New Testament epistle to Timothy > 2 Timothy 3:16.
But the gospel of grace does not stop at Jesus on the cross. Paul says
"we shall be saved by His life," in Romans 5:10.
And
"we shall be saved by His life."
Plus, our Apostle John says we have been perfected in His love making us
"as He is" "in this world." (in 1 John 4:17). And this fits with how Jesus in His Sermon on the Mount says we need to be blessed . . . in our character . . .
"poor in spirit", "meek", "pure in heart" . . . in Matthew chapter five. And what Jesus says is a match with how James says true wisdom is > James 3:17. So, what Jesus has preached is also in the message of James and Paul and other epistle writers. Our Sermon on the Mount is certainly still
"profitable". And the Lord's prayer in John chapter seventeen is still for us . . . all Jesus in His own prayer has claimed for us who hear the words of the disciples > and Jesus prayed all this before He suffered and died for us, on the cross.
In Peter's message in Acts 2 Peter preached the resurrection of Jesus. And in Matthew 26:28 Jesus said the drink of the Lord's Supper is
"My blood of the new covenant, which is shed for the remission of sins." (in Matthew 26:28) So, before His death, already Jesus had told them His blood would be shed for the remission of sins. So, the disciples were clearly told this before Paul was even saved!!!
But before Jesus died, He told them His blood
"is shed for the remission of sins."
All Scripture is
"profitable" (in 2 Timothy 3:16). Well, Jesus said His blood
"is shed for the remission of sins." This is certainly applicable for us. Also, all Jesus says in the Sermon on the Mount is applicable for us. And you might read Paul's love chapter . . . 1 Corinthians 13 . . . which is a match with how Jesus in the Sermon on the Mount says we all need to become in love.