How to Enter Heaven

Death inescapably faces us all. But how can the Christian faith be the main or only requirement to get to Heaven? If Hell and Purgatory are so terrible, how can God permit the souls we are told he loves to go there? These fundamental issues are accessible to those of any faith or none, since God wishes to bring all to Heaven, and has provided a structure for every soul, if it truly desires, to be able to accept his invitation.