"One calls us to rest; the other to fight. One reckons us righteous; the other makes us righteous. One allows for no increase or degrees; the other expects progress and growth. One is a declaration of God about us, the other a work of God in us." | Kevin DeYoungIt is important for us to remember these differences. Over the years, many people have suffered greatly attempting to add to their justification when scripture clearly tells us that by the grace of God, we are provided the faith we need to be saved (Ephesians 2:8-9). However, on the other hand...there are many people who lean so heavily on this grace that they fail to acknowledge the importance of the sanctification process (continued growth in holiness, godliness and Christlike character) as a method to test the true nature of their salvation.
Without question, it is faith alone that justifies a person, but in the same regard the faith that justifies is never alone. So for this reason, we must never separate justification and sanctification. By definition, justification (saving faith) cannot help but produce sanctification (growth in holiness), and the sanctification must flow from the justification in order for it to be real.
These are both wonderful gifts from God which should never be taken lightly. "Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?—unless indeed you fail to meet the test!" (2 Corinthians 13:5)