…and these whom He called, He also justified
When God, the Great Judge of the Universe, passes judgment on your life, He will declare you to be "not guilty"!
But how can that be? You know that you are guilty of doing what was not right many times. You know that your own inner thoughts which no one else can see are so often impure, or angry, or unforgiving, or resentful. You know that you have often spoken in anger when you should not have. You know that you have been hurtful to people. There are times when you have not been honest. How often you have been selfish. There are sins in your life that you hope no one ever finds out about.
What is more, you know that God has already found out about your sins, that nothing is hidden from Him. How then, will God declare you to be "not guilty"?
Only one way: "God made Jesus, who knew no sin [guilt], to be sin [guilty] on our behalf, that we might become the righteousness of God in Him" (2 Corinthians 5:21). This is what it means to be "justified."
When you put your faith in Jesus Christ, Jesus took ALL of your life's guilt, and in exchange gave you His righteousness. He took God's just punishment for you. So now, when God the Judge looks at you, He says in love, "not guilty!"