Nobody Excluded
Clubs have rules which say who may qualify to become a member. Those rules also automatically exclude others. The Jews had rightly believed that they were special to God: but to say that others did not matter to Him, was false. From the time of God's commission to Abraham, it was God's intention that everybody might receive His blessing through His chosen people (Genesis 12:2-3). But, with a few exceptions, many fought against God's authority; and it is the same today.
God's secret plan (mystery) was not to divide people, but to establish the basis on which He could bring them together. That basis was not Abraham, but Jesus Christ. That is why any attempt to bring religions together, on the basis of shared origins, is flawed, because Abraham's purpose was to look forward to Jesus. John 8:56 quotes Jesus as saying, "Your father Abraham rejoiced at the thought of seeing my day; he saw it and was glad." (NIV). The work of Jesus was to give the same rights to the Gentiles as to the Jews: but more than that ... Jesus gave to believing Jews a far greater set of privileges than they ever had before. Only in Jesus can both Jew and Gentile find equality, assurance of forgiveness, direct access into God's presence and peace with Him (Romans 5:1). All who trust in Him are one body to work together and not fight against each other (Colossians 3:15).
The Bible writers express this togetherness in different ways. Jesus said, "I have other sheep that are not of this sheepfold. I must bring them also. They too will listen to my voice, and there shall be one flock and one shepherd." (John 10:16). Paul wrote, "… remember that at that time you were separate from Christ, excluded from citizenship in Israel and foreigners to the covenants of the promise, without hope and without God in the world. But now in Christ Jesus you who once were far away have been brought near by the blood of Christ." (Ephesians 2:12-13). Peter wrote, "But you are a chosen people, a royal priesthood, a holy nation, God's special possession, that you may declare the praises of him who called you out of darkness into his wonderful light. Once you were not a people, but now you are the people of God; once you had not received mercy, but now you have received mercy." (1 Peter 2:9-10)
Those who want to stay within the 'club rules' of religion, will always sidestep Jesus, or attack His right to rule. But those who have come to know Him will understand how amazingly kind and gracious and inclusive He is. God's purpose is to bring everything together under Christ (Ephesians 1:10). That message is the responsibility of us Christians: its intended recipients are people from every 'tribe, language, ethnic group and nation' (Revelation 5:9) ... nobody is left out! So, let's not be timid thinking that Jesus is just for Christians - He is for everybody. Let's tell everybody.