The law incapable of justification

A rookie Paul preaches in a synagogue in Antioch. 

After the law was read he says: 

If you are dead you are dead. 

But if you are raised to live, you are wonderfully alive!

A matter of corruption

Paul says this by firstly explaining God's divine provision and leniency with the nation of Israel since they were set free as slaves from Egypt and how he appointed them leaders and kings and taking it to David, His beloved, he explains how death and corruption came... even in the beloved king David of the old covenant, yet ...

But he, whom God raised again, saw no corruption.

Be it known unto you therefore, men and brethren, that through this man is preached unto you the forgiveness of sins: 

And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses.

Beware therefore, lest that come upon you, which is spoken of in the prophets;

Behold, ye despisers, and wonder, and perish: for I work a work in your days, a work which ye shall in no wise believe, though a man declare it unto you. 

A God who yearns to be near

Paul was quoting the prophets here, Isaiah and Habakkuk and many others who prophesied that a wondrous work would be done amongst the heathen even though God longed for Israel, but they would not let Him near. (Hab 1:5, Isa 28:14, etc. even confirmed by Jesus in Mat 23:37)

... and so the age old story further unfolds ...

And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath.

Now when the congregation was broken up, many of the Jews and religious proselytes followed Paul and Barnabas: who, speaking to them, persuaded them to continue in the grace of God.

And the next sabbath day came almost the whole city together to hear the word of God.

But when the Jews saw the multitudes, they were filled with envy, and spake against those things which were spoken by Paul, contradicting and blaspheming.

Choose Grace

... even today you will find the exact same thing happens as soon as you start teaching about God's Grace, His Goodness, His Kindness ... His Love ... 

Then Paul and Barnabas waxed bold, and said, It was necessary that the word of God should first have been spoken to you: but seeing ye put it from you, and judge yourselves unworthy of everlasting life, lo, we turn to the Gentiles. Act 13:37-46

Paul explains later throughout all his teachings that we are set free from the law by the Spirit of Life! (Rom 8:10, Rom 8:6, Rom 8:2, Gal whole, etc.) 

Truely, following the letter of the law ends in certain death, but the Spirit makes alive forevermore! (2 Cor 3:6)