How do we know that Christians are different from non-Christians?

The distinction between Christians and non-Christians is primarily based on God's sovereign grace and His electing choice. As seen in Romans 11:5-6, the remnant chosen by grace illustrates that it is God's grace that makes believers different, not their actions or virtues. This grace leads to a relational knowledge of God that transforms the believer's heart and mind. When God looks at His people, He sees Christ’s perfection as their substitute, which is a crucial aspect of their identity. Therefore, while both groups are sinners by nature, God views His children through the lens of grace, making them completely accepted in the beloved, unlike the unregenerate.