I was really pondering this and came to the conclusion that no matter what happens in our lives, there is no way we can have a clean slate. None. Even salvation will not make your past disappear. My past, your past, Alece's past will no less shape our futures than if we cut off an arm. It will forever be affected by it.
Whether it is positively, or negatively, that's up to us.
Have you ever tried to write on a chalkboard that hasn't been prepared? SO hard. The chalk doesn't stick properly so it slips and makes it difficult to read. What you are trying to write or draw doesn't adhere to the board. To make your slate effective, you first need to use the side of a stick of chalk and completely colour it in. Thick. Then you dust it off. And then, you can write on it all the better.
When God writes on us with His words, His dreams and His plans for us, it helps that there's a little past residue left for Him to write over.
James 1 says
"Consider it pure joy, my brothers and sisters, whenever you face trials of many kinds, because you know that the testing of your faith produces perseverance. Let perseverance finish its work so that you may be mature and complete, not lacking anything."
While I wouldn't necessarily reccomend giving that verse to someone in the midst of said trial, (as Alece said, save the rhetoric) it is good to remember ourselves that God wants us complete, whole. Not lacking anything. If our lives are proverbial slates, and we have surrendered ourselves into His hands, before we can be effective and usable, first He needs to prepare us. Get us a little dirty... we need to learn the things that are required. I myself have gone around and around in circles with some things, and on about the 3rd time around, I'm asking God "what did I miss? What did I fail to learn?!" It will be messy at times. It will hurt. As my pastor says, there will be spiritual blisters.
Alece, me, you... we've all been prepared. Some have had more chalk scraped over their surfaces than others. Some of us have been dusted off. Some are still in the midst of preperation. Don't wish away your past. Don't ignore it. It's being used by God to shape who you are in Him.
Not lacking anything.