"And other sheep I have which are not of this fold; them also I must bring, and they will hear My voice, and there will be one flock and one shepherd" (NKJV) John 10:16.
Going through the gospel according to John, one could realize that the inspired writer talks more about the Saviour Jesus Christ, His personality on earth and He being the Lamb of God who takes away the sin of the world. (John 1:29). John, the Baptist also saw and testified of the son of God (John 1:34), therefore he didn’t hesitate to tell his disciples about Jesus (John 1:36).
However, when Jesus spoke with His disciples, who were mostly Jews, He used illustrations about Him being the good/chief shepherd and they being the flock (John 10:11; John 10:14; Hebrews 13:20; I Peter 5:4). Inferring, He was enlightening them about His church or kingdom which He built (Matthew 16:13-18) and bought with His own blood (Acts 20:28). The great commission, therefore, rested on His apostles and disciples to make His intent a reality.
Paul, the apostle preached Christ to both Jews and Gentiles (Colossians 1:23). Yes, the Gentiles also needed to hear of Christ and His power to save (Romans 1:16). The house of Cornelius; the Gentile also received Christ. (Acts 10).
Christianity in recent times has been grilled by opinions of modernism and free thinkers/Gnostics who champion the cause of “unity in diversity”. There is a thin line between being one (unity) under one Shepherd and being different in views doctrinally. The former is and must be held fast unto whereas the latter is harmful to our salvation. We must, therefore, stand up firm to make others know the gospel and its power to save, explaining the kingdom of God to them amicably and in sound approach because of the terror of the Lord (II Corinthians 5:11).
We should not relent or perceive that everyone understands the gospel just as we do but rather work diligently to give a reason for the hope that is in us, with meekness and fear (I Peter 3:15). Through prayer and the supply of the Spirit of Jesus Christ (Philippians 1:19), let us strive to make the intent of God to bring the other sheep into the fold a reality.
May God help us to have the good and willing heart to exhort, preach and teach in any opportunity/capacity we get in sound and discerning manner. Amen.