You'll be ok if you repent last minute. But you have to do it like you mean it. If I am not mistaken Christianity is so popular because it's the only religion where you can commit genocide, rape and kill and still go to heaven after repenting. While an unbaptised child or a regular person who hasn't hurt a fly (but does not believe) will have a harder time getting in.
I think you must know very few genuine Christians. You have a very wrong view of us.
God is perfectly able to tell if people really mean it or not.
Repentance isn't just saying a few words to get to heaven, its a complete change of heart and life. Its turning your life around and heading in the other direction. Its getting off the wide road and onto the narrow one.Its following Jesus Christ when its not PC to do so. Its going against the flow.
Yes forgiveness is possible for the worse of sins, IF the one repenting is REALLY serious and genuine. I love it that God gives us a second chance and new beginning.
In the worlds eyes I may be a 'good' person.IE I don't steal, lie, get drunk, cheat, treat people badly, take illegal drugs, swear, etc etc but I am well aware of my weaknesses and failings, and that why I need Jesus Christ. Whether we do really terrible things or smaller ones we are all sinners in the end.