Repent and Believe are the parts of Conversion

"In Mark 1:15 Christ says, 'Repent, and believe in the gospel.' In the first part he denounces our sins, in the latter part he consoles us and shows us the forgiveness of sins. For to believe in the Gospel is not to have the general faith that even the demons have (James 2:19), but, in the true sense, to believe that for Christ's sake the forgiveness of sins has been granted us; this is revealed in the gospel." - The Apology of the Augsburg Confession, Article 7. Penitence, pg. 187-188