But how is it to your credit if you receive a beating for doing wrong and endure it? But if you suffer for doing good and you endure it, this is commendable before God. To this you were called, because Christ suffered for you, leaving you an example, that you should follow in his steps. - 1 Peter 2:20-21
Make no mistake about it, as a believer in the Lord Jesus, you will suffer. As Peter tells us "to this you were called". But why? If, as Luther taught, that Christ suffered and died for us and all that is required for us is "to believe" then why must we also suffer?
First of all, Luther was incorrect. He's clearly contradicted by the scripture here.
We are clearly called to suffer. Peter above makes it clear as does Paul, below, in the book of Acts:
“...We must go through many hardships to enter the kingdom of God,..” - Acts 14:22
Paul goes a bit deeper here in Romans.
"The Spirit you received does not make you slaves, so that you live in fear again; rather, the Spirit you received brought about your adoption to sonship. And by him we cry, “Abba, Father.” The Spirit himself testifies with our spirit that we are God’s children. Now if we are children, then we are heirs—heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory." - Romans 8:15-17
To share in Christ's glory we must also share in his sufferings. It's right there. In plain black and white. There can be no glory without suffering. There can be no salvation without suffering. Why?
Christ's sacrifice began in the upper room, before he suffered. It began with the third cup of the Passover Seder, the Cup of Redemption. In Matthew 26:26-28 we see the beginning of his Sacrifice.
While they were eating, Jesus took bread, and when he had given thanks, he broke it and gave it to his disciples, saying, “Take and eat; this is my body.” Then he took a cup, and when he had given thanks, he gave it to them, saying, “Drink from it, all of you. This is my blood of the covenant, which is poured out for many for the forgiveness of sins."
If Christ turning the un-leaven bread and the wine into the body and blood of the new covenant was sufficient for the salvation of all, then why did he have to go through with the suffering of the cross?
Because payment must be made.
In Exodus 24:6-8 we see the below:
Moses took half of the blood and put it in bowls, and the other half he splashed against the altar. Then he took the Book of the Covenant and read it to the people. They responded, “We will do everything the Lord has said; we will obey.” Moses then took the blood, sprinkled it on the people and said, “This is the blood of the covenant that the Lord has made with you in accordance with all these words."
This looks extremely similar to what Christ said during the Third Cup of his Passover Seder dinner.
The Covenant must be sealed with blood. Just as Moses and the Israelites made animal sacrifices to mark the sealing of the covenant between themselves and God, Christ's death on the cross was the blood that was required to seal the New Covenant.
But again, WHY must we suffer?
Because your suffering contains in it the potential for redemption.
Go back and re-read Romans 8:15-17.
we are heirs—heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory
Suffering is required to partake in the Glory of Christ. It is, in effect, this same form of payment. It is the substance that love converts into a sacrifice.
How? When you take in The Eucharist, you are taking in the body, blood, soul and divinity of Jesus. You are taking in the "divine nature" of Christ himself (2 Peter). You are taking in the pure form of sacrificial love.
However, love alone does not make a sacrifice. Love turns suffering into a sacrifice. Just as Christ's love turned his suffering into the perfect sacrifice, his divine nature turns our suffering into our sacrifice.
So, rejoice in your sufferings, as James said in that famous "epistle of straw":
Consider it pure joy, my brothers and sisters, whenever you face trials of many kinds, because you know that the testing of your faith produces perseverance. Let perseverance finish its work so that you may be mature and complete, not lacking anything.