Jesus was friends with unbelievers. He was called a“friend of sinners” (Matt. 11:10). Paul, therefore, instructed the Corinthians to befriend/associate with unbelievers( 1 Corinthians 5:9-11). He expected them to socialize with unbelievers ( 1 Corinthians 10:27), and he was focused on reaching lost people (1Corinthians 9:19-23).
The Apostle Paul said that while we were sinners, God died for us (Romans 5:8) and that while we were enemies, we were reconciled to God through the death of Jesus and have been saved by His life (Romans 5:10).
Just as God reconciled us to Himself, He wants us to become ministers of reconciliation, sharing the message of hope with other people (2 Corinthians 5:16-20), especially unbelieving friends. That starts with something as simple as being a friend.