The book of Jonah is all about the lack of love for one's enemies. God calls Jonah to go to Nineveh and Jonah decides that this plan of God's is not for him. Why? Because Jonah knows that the Ninevites will repent and turn from their sins and God will forgive them and not destroy them (Jonah 4:1-3). Jonah knows that God's heart is to see people turn from their sin so he can show grace and compassion and forgiveness. And Jonah doesn't want to see the Ninevites receive grace and salvation. He'd much rather see them destroyed. Jonah did deliver God's message to the Ninevites, but he wasn't happy about it or their repentance.
Ananias didn't want to go to Saul. He knew Saul's reputation and why Saul had come to Damascus. He probably would've been content to let Saul sit wherever he was and be blind. But then he would've missed out on being a part of what God was doing and what God was going to do. Ananias heals and baptizes Saul and instantly, God had changed Saul.
"Saul spent several days with the disciples in Damascus. At once he began to preach in the synagoguesthat Jesus is the Son of God. All those who heard him were astonished and asked, “Isn’t he the man who raised havoc in Jerusalem among those who call on this name? And hasn’t he come here to take them as prisoners to the chief priests?” Yet Saul grew more and more powerful and baffled the Jews living in Damascus by proving that Jesus is the Messiah." (Acts 9:19b-22)
Of course those Jews were skeptical of Saul and tried to kill him. Loving your enemies is hard. Even when you can see they've been changed.
Peter was a little hesitant about meeting Cornelius but he couldn't deny that God was at work.
"Then Peter began to speak: “I now realize how true it is that God does not show favoritism but accepts from every nation the one who fears him and does what is right." (Acts 10:34-35)
"While Peter was still speaking these words, the Holy Spirit came on all who heard the message. The circumcised believers who had come with Peter were astonished that the gift of the Holy Spirit had been poured out even on Gentiles. For they heard them speaking in tongues[b] and praising God.
Then Peter said, “Surely no one can stand in the way of their being baptized with water. They have received the Holy Spirit just as we have.” (Acts 10:44-47)