The Second Part is about the articles that pertain to the office and work of Jesus Christ, or to our redemption.
Here is the first and chief article:

1] That Jesus Christ, our God and Lord, died for our sins, and was raised again for our justification, Rom. 4:25.

2] And He alone is the Lamb of God which taketh away the sins of the world, John 1:29; and God has laid upon Him the iniquities of us all, Is. 53:6.

3] Likewise: All have sinned and are justified without merit [freely, and without their own works or merits] by His grace, through the redemption that is in Christ Jesus, in His blood, Rom. 3:23f

4] Now, since it is necessary to believe this, and it cannot be otherwise acquired or apprehended by any work, law, or merit, it is clear and certain that this faith alone justifies us as St. Paul says, Rom. 3:28: For we conclude that a man is justified by faith, without the deeds of the Law. Likewise 3:26: That He might be just, and the Justifier of him which believeth in Christ.

5] Of this article nothing can be yielded or surrendered [nor can anything be granted or permitted contrary to the same], even though heaven and earth, and whatever will not abide, should sink to ruin. For there is none other name under heaven, given among men whereby we must be saved, says Peter, Acts 4:12. And with His stripes we are healed, Is. 53:5. And upon this article all things depend which we teach and practice in opposition to the Pope, the devil, and the [whole] world. Therefore, we must be sure concerning this doctrine, and not doubt; for otherwise all is lost, and the Pope and devil and all things gain the victory and suit over us.

Book of Concord – Smalcald Articles – Part II Article I