"After much discussion, Peter got up and addressed them: 'Brothers, you know that some time ago God made a choice among you that the Gentiles might hear from my lips the message of the gospel and believe. God, who knows the heart, showed that he accepted them by giving the Holy Spirit to them, just as he did to us. He made no distinction between us and them, for he purified their hearts by faith. Now then, why do you try to test God by putting on the necks of the disciples a yoke that neither we nor our fathers have been able to bear? No! We believe it is through the grace of our Lord Jesus that we are saved, just as they are'" (Acts 15:7-11, NIV).
God knows the heart. When he looked into the hearts of Cornelius, his family, and his friends as they were hearing the good news about Christ, God saw hearts that had been affected by his grace. He saw faith in Jesus Christ and a willingness to obey; and he accepted those new believers. Before the other Christians accepted them (because of ethnic differences), God accepted them. Before they had expressed their faith and their willingness to obey, God accepted them. He knew their hearts. He knew they believed. He knew they would follow his instructions. Even if they would have been rejected by the church (which they were not, to the credit of the church), God saw their hearts and accepted them. What a great God!