Unless you conquer the past, you cannot focus on your future. If your past must be over, you have to outgrow it. In other words, if you desire to focus on your future, you must first conquer your past. You must be forward looking because you cannot look in different directions at the same time. The One who determines our future is our Lord Jesus Christ. He does not consult our past to determine our future. If He were to do so, we would not be here today.
Satan discusses our past because that is the only information he has about us. Each time we want to focus on our future, satan is there to remind us of our unworthy past in order to provoke our guilt and tarnish our future thereby. He has no other business than to derail us from our course. This is why the Bible warns us against taking journeys into the past; it is very dangerous.