Christ came preaching the Gospel, the Good News about Himself and His plan to redeem mankind and reconcile them to the Father. This Good News had an impact on both believing Gentiles and believing Jews. For the Gentile, the great truth they were coming to understand was that they were welcome into God's presence when they put their faith and trust in Jesus Christ. This was having peace with God, and this especially touched the Gentile who were made painfully aware that they were far from God.
This same Good News impacted the Jew by showing them that simply calling one's self a Jew didn't make them right with God. Just because they were "near" to the truth wasn't going to save them. They, too, needed to trust Jesus Christ to be their Savior and Messiah. Knowing the truth is not the same as putting your faith in the Living Truth, Jesus!