The opposite of antinomianism is legalism and it is the belief that salvation is based on good works apart from faith and apart from grace. Jesus condemned this view of the Pharisees. Paul condemned this view of the Judaizers, especially in the books of Galatians and Romans. Antinomianism, on the other hand, says salvation is based on faith in God and therefore obedience to God's law is not necessary at any stage in a Christian's life.
The two extreme opposite concepts of legalism and antinomianism are both totally opposed to the teaching of the Bible.
6 But now Jesus, our High Priest, has been given a ministry that is far superior to the old priesthood, for he is the one who mediates for us a far better covenant with God, based on better promises.
7 If the first covenant had been faultless, there would have been no need for a second covenant to replace it. 8But when God found fault with the people, he said:
“The day is coming, says the Lord,
when I will make a new covenant
with the people of Israel and Judah.
9 This covenant will not be like the one
I made with their ancestors
when I took them by the hand
and led them out of the land of Egypt.
They did not remain faithful to my covenant,
so I turned my back on them, says the Lord.
10 But this is the new covenant I will make
with the people of Israel on that day, says the Lord:
I will put my laws in their minds,
and I will write them on their hearts.
I will be their God,
and they will be my people.
11 And they will not need to teach their neighbors,
nor will they need to teach their relatives,
saying, ‘You should know the Lord.’
For everyone, from the least to the greatest,
will know me already.
12 And I will forgive their wickedness,
and I will never again remember their sins.”