We worship the way we do because each part of the worship service has significance in our relationship with God.

Below is a summary of what each part means that comes from one of our sister churches: Good Shepherd Lutheran Church, Moncton, New Brunswick, Canada:

The Prelude
Music helps draw us into an attitude of prayer and praise.
The Ringing of the Bells
This is a call to Gods people “to enter the lord’s gates with thanksgiving and His courts with praise” (Psalm 100:4).
A Hymn of
We are a “singing church,” so we follow the advice of the apostle Paul to teach and admonish “one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the lord” (Colossians 3:16).  This hymn may be one of praise, prayer, or reflection on the season of the church year.
The Invocation
We call upon God to be present with us. We worship the triune God, remembering our Baptism in His name*.  Amen means “So be it, it is true!”
* Matt. 28:19;  Matt. 18:20;  Eph. 2:18.
The Confession
of Sins
We examine ourselves and publicly confess our sins. Such a confession at the beginning of the service provides a climate of acceptance. In spite of our sins, we are accepted by God, and in turn we can accept each other.
* I John 1:8-10 [Rom. 7:14-8:4].
The Absolution
Christ said to his disciples, “If you forgive anyone his sins, they are forgiven”*.  The pastor speaks for God and announces God’s cleansing forgiveness to those who made confession.
* John 20:23.
From the time of the apostles down through today, an important part of the service has been the reading of the Scriptures, including the Old Testament Lesson, the Epistle Lesson from the New Testament, and the Gospel Lesson.  The reason for including these readings is the scriptural principal that God’s Word is the only rule and guide for Christian faith and living.  The Service of the Word concludes with the sermon (which is the preached word), the church’s confession of faith in response to God’s Word, and the prayers of God’s people.
The Introit of the Day
Introit is a Latin word meaning “he enters into.”  The Introit is a part of a psalm or a hymn that announces the theme of the day and begins the Service of the Word.  Many years ago the faithful would meet outside and then proceed into the church.  The pastor and the people would chant psalms as they entered the sanctuary.
The Introit traditionally consists of an Antiphon, or refrain, a Psalm or a series of Psalm verses, the Gloria Patri*, and the Antiphon repeated.* Rom. 16:27;  Eph. 3:21;  Phil. 4:20;  Rev. 1:6, 8.
The Kyrie
Kyrie is a Greek word meaning “O Lord.” It is a cry to the Lord for help and strength*.  In ancient times, the crowds would shout “Lord, have mercy” as the King entered their town.  The church has taken over his prayer to greet its King Jesus Christ in the church service.  As the people so long ago expected help from their King, so we Christians expect help from our Savior.
* Matt. 9:27;  Matt. 15:22;  Matt. 20:30-31;  Luke 17:13.
The Hymn of Praise
Two hymns of praise, which vary depending if the Lord’s Supper is celebrated, give the congregation the opportunity to praise God and express joy because Jesus is our victorious Savior.  During Advent and Lent, the hymn of praise is omitted.
* “Glory to God in the highest,” Luke 2:14; “This is the feast of victory,” Rev. 5:12f.
The Salutation
In the Salutation, the pastor and the congregation great each other in the Lord’s name.
* Ruth 2:4; Luke 1:28; II Thess. 3:16; II Tim. 4:22.
The Collect of the Day
The main thoughts of the day are collected, or summarized in this short prayer.  The collects for the reason of the church year have come to us from the rich treasury of the church’s heritage.
The First Lesson
The first reading is from the Old Testament, except during the Easter season when it is from the Book of Acts.  This reading usually relates to the Gospel of the day.* I Tim. 4:13.
The Gradual
Gradual, a Latin expression meaning “step,” is a scripture passage for each season of the church year.  It is a response to the First Lesson and a bridge to the Second Lesson.  Sometimes a psalm is sung or spoken.
The Second Lesson
The second reading is from one of the epistles (letters) in the New Testament.
The Verse
A verse from the holy scriptures is usually sung in preparation for the reading of the Gospel.  There are general verses* as well as specific verses for the seasons of the church year.
* John 6:68; Joel 2:13 (through lent).
The Holy Gospel
The Gospel Lesson is a selection from the accounts of the life of our Lord recorded by the four evangelists, St. Matthew, St. Mark, St. Luke, and St. John.  Because Christ is with us in the Gospel reading, we stand to honor his presence.  We also sing versicles (short verses) before and after the reading of the Gospel.  The minister reads the Gospel while standing among the people.  He may be flanked by acolytes carrying candles who proclaim Jesus and his word as the “light of the world.”
The Hymn of the Day
This hymn follows the theme of the readings and set the stage for the sermon. Suggested hymns of the day are listed on page 976-78 of Lutheran Worship.
The Sermon
The Pastor proclaims God’s Word and applies that word to modern life and problems.  He stresses both what God demands of us that show us our sin (the Law) and what God does for us through Jesus Christ (the Gospel).
The Creed
After hearing the word of God read and proclaimed, the worshiper responds with his confession of faith in the words of the Nicene Creed.  It is customary for the Nicene Creed to be spoken when Holy Communion is celebrated and on major festivals.  The Apostles’ Creed is used at other times. This can also be confessed before the sermon as an affirmation of faith in the written Word of God.* I Cor. 15:1ff;  I Pet. 3:18ff;  I Tim. 3:16.
The Prayers
This prayer in the service follows the directive of the Apostle Paul to young Timothy, a pastor: “I urge, then, first of all, that requests, prayers, intercession and thanksgiving be made for everyone – for Kings and all those in authority, that we may live in peaceful and quiet lives in all godliness and holiness”*.  For this reason, prayers are included for the whole church, the nations, those in need, the parish, and special concerns.* I Tim. 2:1-2.
The church has confessed its sins and been forgiven, and its faith has been nurtured through hearing the Word.  The church now reaches a climax of the worship experience in the celebration of the sacrament of Holy Communion.  The following parts of the liturgy help the worshipers partake of the holy meal thoughtfully, thankfully, and joyfully.
The Offering
The gifts of God’s people are a response to God’s blessings “as God has prospered them” (1 Corinthians 16:2).  Our offerings are for the support of the church.  They enable the church to provide the written and spoken word of God to those in our community and beyond, Christian education, and pastoral care, food, clothing, shelter, and other physical and spiritual to those in need so that they might hear the Gospel and be given faith through the power of the Holy Spirit.
The Offertory
As the offerings are brought to the Lord’s table, the worshipers sing the offertory* to express gratitude for all God’s blessings, dedicate themselves to God, and request His continued blessings.
* “What shall I render to the Lord,” Ps. 116:12, 17, 13-14, 19;  “Create in me a clean heart”, Ps. 51:10-12.
The Preface
Preface means “introduction.”  The pastor and people get ready to celebrate the Holy Meal by greeting each other and with an exhortation as how to celebrate the meal.* Cf. “Salutation”;  Lam. 3:41;  Ps. 86.4.
Proper Preface
These words state why we should give thanks using words and ideas appropriate for the season of the church year.
* Pss. 69:30;  95:2; 100:4;  107:22; 116:17;  147:7.
The Sanctus
Sanctus is a Latin word meaning “Holy.”  The Sanctus contains words from Isaiah’s vision of God (Isaiah 6:3) and the crowd’s response on Palm Sunday when Jesus entered the city of Jerusalem (Matthew 21:9).  We join them in spirit by singing their words as we anticipate Christ’s coming in the sacrament.* Is. 6:3;  Matt. 21:9 (Mk 11:9);  Ps. 118:25-26.
The Lord’s Prayer
We pray to God as our Father using the prayer of the family of God* because the Lord’s Supper is our family meal.
* Matt. 6:9ff;  Luke 11:2ff.
The Words of
The pastor speaks the words which Jesus spoke when He instituted the Supper with His disciples in the Upper Room.  With these words the bread and wine are consecrated, that is, set apart for God’s use in the special meal.
* 1 Corinthians 11:23-26; Matthew 26:26-28; Mark 14:22-24; Luke 22:19-20.
The Peace
The greetings of peace which Jesus spoke on the first Easter is shared before we approach the altar to receive Him.  In the Lord’s Supper, the body and blood of Christ are truly present in, with, and under the bread and wine.
* John 14:27;  John 20:19-21.
The Agnus Dei
Agnus Dei is a Latin phrase meaning “Lamb of God.”  John the Baptist spoke these words as he pointed to Jesus coming toward him (John 1:29).  As Christ comes to us in the Holy Supper, we recognize him as the Lamb of God sacrificed for us to free us from the bondage of sin and death.* John 1:29; Is. 53:7.
The Administration
of the Supper
As we kneel at the Lord’s Table, the pastor invites us, “Take, eat; this is the true body of our Lord and Savior Jesus Christ, given into death for your sins.  Take, drink, this is the true blood of our Lord and Savior Jesus Christ, shed for the forgiveness of your sins.”  After we receive the Sacrament we hear the comforting words spoken by the pastor, “The body and blood of our Lord strengthen and preserve you in the true faith to life everlasting.”  We respond, “Amen,” for this is our sincere desire. It is a good practice to offer a silent prayer of thanks when we return to our pews.  While the meal is being distributed, the congregation and/or the choir sing one or more hymns.
The Post-Communion
“Thank the Lord,” “Lord, now let Your servant go in peace,” or an appropriate hymn is sung.  The purpose is to offer our thanks and express our faith in what God has done for us and promised to do for us in the future.
* “Lord, now you let Your servant go in peace”, Luke 2:29f.
The Prayer of Thanks
Once again we express our appreciation to our gracious God for giving us this Holy Meal through Jesus Christ, our Lord and Savior.* Pss. 107:1;  118:1.
The Blessing
The blessing spoken by the pastor is the Aaronic benediction, the blessing God first gave to Aaron and the other priests to speak to the people of Israel.  Jesus Christ, our High Priest, has come to us in a special way through this Holy Meal.  The blessing is God’s promise that Christ will go with us as we leave the church and return to the world to serve Him.  We sing “Amen” to affirm the blessing; “So be it — it is true!”
* Numbers 6:23-27.