Lets say you are a devout christian who follows all the rules of god to get to heaven But?

lets also so say that darn ole devil tempts you to do something evil for the first time in your life. and you do the evil deed. Right after you do this evil deed you get creamed by a speeding train, Wham instant death. Now you didn't have any time to repent and be sorry for your evil deed, are you going to go to heaven Or has you wonderful god thought (well he knew the rules and poof your gone)?