First reading Numbers 21:4-9

If anyone was bitten by a serpent, he looked up at the bronze serpent and lived

On the way through the wilderness the people lost patience. They spoke against God and against Moses, ‘Why did you bring us out of Egypt to die in this wilderness? For there is neither bread nor water here; we are sick of this unsatisfying food.’
  At this God sent fiery serpents among the people; their bite brought death to many in Israel. The people came and said to Moses, ‘We have sinned by speaking against the Lord and against you. Intercede for us with the Lord to save us from these serpents.’ Moses interceded for the people, and the Lord answered him, ‘Make a fiery serpent and put it on a standard. If anyone is bitten and looks at it, he shall live.’ So Moses fashioned a bronze serpent which he put on a standard, and if anyone was bitten by a serpent, he looked at the bronze serpent and lived.

Responsorial Psalm 77(78):1-2,34-38

Never forget the deeds of the Lord.
Give heed, my people, to my teaching;
  turn your ear to the words of my mouth.
I will open my mouth in a parable
  and reveal hidden lessons of the past.
When he slew them then they would seek him,
  return and seek him in earnest.
They would remember that God was their rock,
  God the Most High their redeemer.
But the words they spoke were mere flattery;
  they lied to him with their lips.
For their hearts were not truly with him;
  they were not faithful to his covenant.
Yet he who is full of compassion
  forgave them their sin and spared them.
So often he held back his anger
  when he might have stirred up his rage.

Gospel John 3:13-17

God sent his Son so that through him the world might be saved

Jesus said to Nicodemus:
‘No one has gone up to heaven
except the one who came down from heaven,
the Son of Man who is in heaven;
and the Son of Man must be lifted up
as Moses lifted up the serpent in the desert,
so that everyone who believes may have eternal life in him.
Yes, God loved the world so much that he gave his only Son,
so that everyone who believes in him may not be lost
but may have eternal life.
For God sent his Son into the world
not to condemn the world,
but so that through him the world might be saved.’