What is the Biblical basis of the idea that men can be given authority to forgive sins?
St. John speaks of it in his Gospel (John 20:19-23):
Jesus Appears to His Disciples
19 On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, “Peace ...
You may be thinking of Paul in his letter to the Romans:
For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek.
9 There will be tribulation and distress for every human being who does evil, the Jew first and also the Greek, 10 but glory and honor ...
I am not aware of Catholic teaching on the subject. However "love your neighbour as yourself is a quote from leviticus 19:8.
Rabbai Hillel is often cited as the first person who uses it as a summary of the law. You can read about that here
When Jesus also includes the ...