When I first heard this doctrine, every Baptist cell in my body cried out, "That's impossible! All my sins were forgiven two thousand years ago on the cross of Calvary. It is impossible for man to "do" anything to have his sins forgiven!"
After much study on this issue, here is the best way I have found to explain to Baptists/evangelicals this Lutheran/orthodox doctrine: Ask your Baptist/evangelical friend this question: Do you pray to ask God to forgive you of your daily sins?
His answer will most likely be, "Yes".
So why do you pray to God to ask for forgiveness of sins that He has already forgiven? He paid the price for all your sins, and forgave all your sins, two thousand years ago on the cross of Calvary, including the ones you committed today. So why do you need to ask for forgiveness for sins that are already forgiven??
The correct answer should be: All Christians pray to God for the forgiveness of our daily sins for two reasons:
1) God tells us to do it.
2) We do it for the personal benefit of unburdening our consciences: by praying to God for forgiveness of our daily sins we re-experience Christ's forgiveness that we know we already have! It is a wonderful therapeutic exercise designed by God to relieve our consciences of the shame and self-judgment that comes with being sinners, sinners who can't help but sin in thought and deed every single day of our lives!
In the Lord's Supper, we Lutherans believe that we experience this same forgiveness of sins when we sincerely repent of our sins while kneeling at the altar, receiving in our mouths the Bread and Wine. Our sins (our consciences) are washed clean, we are forgiven again. We are not partaking of the Lord's Supper to forgive sins that have not already been forgiven. We are not partaking of the Lord's Supper to help save us. We are already saved!
But even more than re-experiencing forgiveness, as all Christians experience when they ask for forgiveness of daily sins, we Lutherans re-experience our salvation...each and every time that we partake of the Bread and Wine in the Lord's Supper. We believe that we are, in a supernatural way, being taken back in time to the Cross of Calvary, and as we eat the Bread and the Wine, we are touching the Body and Blood of our Lord and Savior on the cross, and as we are in contact with his blood, in this supernatural experience, we once again experience the washing away of our sins!
Our participation in the Lord's Supper isn't doing anything to help save us from hell...we are already saved! Baptists are right: no work of man can help save us. Lutherans do not keep a log of how many times we have taken Communion to make sure that we get into heaven when we die. We are not being saved in the Lord's Supper, but we are being saved...all over again, in a supernatural experience, each and every time we partake of Holy Communion.
Just as Baptists/evangelicals re-experience forgiveness of sins when they pray to God for the forgiveness of their daily sins, Lutherans believe that if we come to the Lord's Table with truly contrite hearts, we will re-experience Christ's forgiveness and his salvation, all over again. It is a beautiful, marvelous, super-natural experience.
Matthew 26:26-29 English Standard Version (ESV)
Institution of the Lord's Supper26 Now as they were eating, Jesus took bread, and after blessing it broke it and gave it to the disciples, and said, “Take, eat; this is my body.” 27 And he took a cup, and when he had given thanks he gave it to them, saying, “Drink of it, all of you, 28 for this is my blood of the[a] covenant, which is poured out for many for the forgiveness of sins. 29 I tell you I will not drink again of this fruit of the vine until that day when I drink it new with you in my Father's kingdom.”
Footnotes: Matthew 26:28 Some manuscripts insert new
So where do Lutherans and other orthodox Christians get the idea that during the Lord's Supper we are re-experiencing our salvation at Calvary? Answer: from the Jews!
When Jesus and his disciples met in the Upper Room and celebrated the first Lord's Supper, were they there to celebrate a completely new Christian ritual? No. So what were they doing?
They were celebrating the Jewish Passover. They were following a tradition that started in Egypt with the Exodus of the Jewish people from slavery; the same tradition celebrated by Jews around the world today. On the Jewish Passover, Jews celebrate a seder, a meal, commemorating the hurried meal that the Jewish slaves of Egypt put together, before their escape with Moses from the angry Pharoah.
Here is what Jews say about this meal, the Passover Seder:
"Participation in the seder lets one symbolically and vicariously relive the Exodus, where past and present merge."
Jews believe that when they participate in a Passover Seder that they are vicariously reliving the Exodus from Egypt! So the Passover seder is not just a symbolic memorial...they are really there...in EGYPT, eating and drinking with their ancient ancestors in the first Passover meal!
So when Jesus met with his disciples that Passover evening, they expected to have a traditional, Jewish Passover Seder. His disciples were planning on reliving, re-experiencing the Jewish Exodus from Egypt, as they had done once a year for their entire lives. They were expecting to eat the Passover lamb and drink the Passover wine, as Jews still do today.
However, Jesus had a surprise for them. Instead of serving the traditional lamb and wine, Jesus serves...himself! Jesus was demonstrating to his disciples that HE is the passover lamb. HE is the fulfillment of the Passover. When he told them "do this in remembrance of me", what he was saying was this, "from now on when you celebrate the "seder", you will no longer be looking back and reliving the events in Egypt, you will be looking back to my death on the cross, where I shed my blood and my body was broken for you...this is the vicarious experience that you will relive each and every time you partake of my seder. And by the way, don't just do it once a year...do it often until I come back!"
So just as Jews today re-experience the Exodus from Egypt in the Jewish Passover seder, now the followers of Christ, Christians, celebrate the fulfilled Passover seder---the Lord's seder, the Lord's meal, the Lord's Supper...Holy Communion, reliving the event when our Passover Lamb's blood was poured out on "the door posts" of the cross for our redemption! If we are experiencing this seder/meal vicariously, as the Jews have always taught that it should be viewed, then it is REAL, not just symbolic! The food of the meal is real. The bread is real flesh. The wine is real blood.
This is why Lutherans believe that we re-experience our salvation every time that we partake of the Lord's Supper because that is how the early Jewish Christians saw the first and subsequent Lord's Suppers...it was a seder, and in a seder you vicariously return to "Egypt". We Christians vicariously return to our "Exodus", to our point of liberation from our bondage...the Cross of Calvary! And our seder meal is no longer lambshank and wine. It is the Bread of Life and the Blood of Redemption! In the Christian Passover seder we feast on the flesh and blood of the one and only Lamb of God...who takes away the sins of the world.
For a Jewish explanation of the Passover seder, click on this link: