He could stay, and suffer with a failing body, or go to heaven and join his loving family on the other side of life.
There is one heaven, so shouldn't we use the with heaven?
You go to bed when you are sleepy.
You go to school when you are a student.
Some believe you go to heaven when you die.
This form without an article refers to the behavior or action as behavior or action, i.e. in the abstract or "in general", rather than to a particular bed, school, or heaven, as the case would be with the definite article, the, and rather than to no bed, school, or heaven in particular, but still to some bed, school, or heaven, as the case would be with the indefinite article a.
No, because assuming the subject follows one of the Christian faiths (or any faith with a heaven really), the heaven* being referred to is Heaven, a specific place with a proper name.
It should be written:
...or go to Heaven and join his family...
*Heaven spoken of as a concept, as above, would take an article.
A) "I went to a park." <== could mean any park
B) I went to the park." <== maybe one of many parks, but we're supposed to know which one is meant from context or other reasons.
C) "I went to the Department of Education." <== one of many departments, and then we supply context to tell you which one
D) "I went to Disneyland." <== Proper Noun: only one in existence and it's called this (no "the" is used)
So which pattern would you use for "heaven" or "hell" ? D). It was probably spelled with a capital 'H' originally.
In order not to sound stilted and still refer to multiple ideas of heaven, it is best to refer to the specific heaven in question. For example:
...the Christian heaven...
...the Pastafarian heaven...
...heaven for Christians...
...heaven for Pastafarians...