Jesus showed he has God's authority by healing physical infirmity:
9 Which is easier, to tell the paralytic, ‘Your sins are forgiven;’ or to say, ‘Arise, and take up your bed, and walk?’ 10 But that you may know that the Son of Man has authority on earth to forgive sins”—he said to the paralytic— 11 “I tell you, arise, take up your mat, and go to your house.”
12 He arose, and immediately took up the mat, and went out in front of them all; so that they were all amazed, and glorified God, saying, “We never saw anything like this!”
The first century apostles gave the clear message that Jesus came to enable our sins to be forgiven:
31 God exalted him with his right hand to be a Prince and a Saviour, to give repentance to Israel, and remission of sins.
The apopstle Paul gives a similar message in his letters:
7 in whom we have our redemption through his blood, the forgiveness of our trespasses, according to the riches of his grace,
14 in whom we have our redemption, the forgiveness of our sins.