There are a number of recurring phrases you will hear in a Lutheran church, so it's helpful to know what they mean. If you want to learn more about what Lutherans believe, click here.
sola fide / "Faith alone"
We cannot be justified before God by own strength, merits, or works, but are freely justified for Christ's sake, through faith, when we believe that we are received into favor, and that our sins are forgiven for Christ's sake, who, by His death, has made satisfaction for our sins. This faith God imputes for righteousness in His sight.
Law & gospel
If one were to “boil” the Bible down to its basic components, one would find two distinctly different doctrines, The Law and The Gospel. The main function of the Law is to show us our unrighteousness. When the Law shows us our sin, however, it doesn't give us any power, energy or desire to keep it. It serves mainly as a mirror, reflecting back to us who we are and how we have failed to keep God’s revealed will for us in all its parts (Romans 3:19-20). The Law can only declare you guilty. The main function of the Gospel is to show us what God did to save us from our sinful rebellion and our disregard for God’s law. God saves us by calling us to faith in Jesus Christ, whose suffering, death and resurrection atoned (or covered) our sin and who has imputed (or credited) His perfect righteousness to us. The Law can only declare you guilty. Jesus declares the guilty forgiven. (John 5:39 ; 20:30-31; Romans 4:5 ; 10:17;2 Timothy 3:15ff; and 1 John 1:8-9 ).
means of grace
Although God is present and operates everywhere throughout all creation and the whole earth is therefore full of the temporal bounties and blessings of God, still we hold with Scripture that God offers and communicates to men the forgiveness of sins only through the external means of grace ordained by Him. These means of grace are 1) the Word of the Gospel, and the Sacraments of 2) Holy Baptism and of 3) the Lord's Supper.
The Word of the Gospel promises and applies the grace of God, works faith and thus regenerates man, and gives the Holy Ghost. Baptism, too, is applied for the remission of sins and is therefore a washing of regeneration and renewing of the Holy Ghost. Likewise, the Lord's Supper is none other than the communication and sealing of the forgiveness of sins, as the words declare: "Given for you," and: "Shed for you for the remission of sins."