This is an essay providing an argument for the protestant belief that we are saved by faith only, or in Latin, Sola Fide.
Sola Fide - By Faith Alone
There is just one way into heaven: believe that
Jesus is the son of
God.
I tell you the truth, whoever hears my word and believes him who sent me has eternal life and will not be condemned; he has crossed over from death to life (John 5:24).
Therefore we conclude that a man is justified by faith apart from the deeds of the law (Romans 3:28).
From these, and scores of other verses, we must know one thing, if we learn nothing else from God's Word: we are saved by faith alone. There is no act you can preform and no deed you can do to earn your way into God's presence.
One sin (and everyone has sinned) sets you so far apart from God's glory that not even dedicating your life to the refugees in Somalia will atone for it. John the Baptist to Mother Theresa to yours truly have sinned, and there is no hope of being forgiven on account of being a good person.
Yet, God's grace is so great that He sent His son to take our punishment. All we must do is allow Him to take our punishment and all our sins will be wiped away. No deeds you perform afterward will make you better or worse in God's eyes - there is no "more perfect." Jesus certainly did not think the thief on the cross next to His was about to perform some deeds to achieve holiness, but he was still promised a place in paradise.
Under the Old Covenant, the Jewish people were to follow a very strict set of laws to remain in God's favor. If they ever made a mistake they were to sacrifice an animal. This would postpone punishment, but never made them entirely blameless. When Jesus died on the cross, we entered into a new covenant. He was a perfect sacrifice - no longer would God's children need to kill animals to stay in His favor.
All of this is not to say that deeds are not important. They are, but they are not necessary for salvation. We are improved as people, grow closer to God, receive greater rewards, and achieve God's will (not to mention you will want to do them anyway when you have been saved). Still, nothing you can do will cause you to be holy; only Jesus can do that.
Sola Scriptura - By Scripture Alone
Sola Fide - By Faith Alone
Sola Gratia - By Grace Alone
Solo Christo - By Christ Alone
Soli Deo Gloria - Glory to God Alone