A "Saint," is someone officially recognized as definitely (probably ... in all likelihood, etc.)having gone to Heaven. That's all. The rest is theater.
On a strictly theoretical, theological level, this "official recognition," is non-denominational. However, the Pope traditionally makes the most of the opportunity to certify dead folks as "Saints."
The Bishop of Rome and his organization may be the best at the "Saint" process, but they certainly are not alone. If one should survive drinking strychnine or snakebite at a service in West Virginia, or be from Salt Lake City, the Pope might not be unduly impressed, but other saint-sanctioning bodies will take up the slack.
Now I'm confused... Why are so many books of the Bible written to people in Heaven? That's just weird.