Why not sin?
First - we need to get rid of the double-negative theology implicit in "why not sin" and reconceptualise the problem as the positively aspirational: "Why be Good?".
After all; I understand sin to be any and all departures from the positive situation of living in full harmony with the wholly-loving aims and nature of God's ongoing creation.
"A sin" is thus any thing - any impulse, thought, action - which does not harmonize with divine love. There are therefore innumerable "sins", and everybody "sins" nearly-all of the time.
Since sin is best defined in terms of departure from Good; it is clearly much better (positively) to aim at being-Good - rather than (negatively) trying not-to-do not-Good!
(To get some-place - i.e. heaven - it is insufficient to be told when we stray off the path; we most need to know where we are going, and how to get there!)
For me; the answer to "Why be Good?" is that I desire to live "wholly by Love" - to live in accordance with God's ongoing divine creation - which derives from God's love, and is motivated by love.
Indeed; anyone who wants Heaven, surely wants to live by love?
(Else why would he want Heaven forever?)
Expressed otherwise: Why on earth would anyone who ultimately desired to live eternally in complete accordance with love; not want to do so here-and-now, and all of the time?
Wanting to live by love is just characteristic of the kind-of-person who wants eternally to dwell in Heaven after death.
Yet of course we are tempted - over and again, very frequently - to live other-than by full accordance with love: to live out-of-harmony with divine creation, because it is short-term gratifying for us to do so.
And therefore we often fail to resist these temptations; and we sin for much of the time.
So we do not, as a matter of fact, resist temptation - and we do instead often choose to live out-of-harmony with divine creation.
Given that fact; it might be asked: why should we even try to resist temptation?
Why - since we fail all the time, and will continue to fail - don't we just accept the reality of sin; and sin whenever it is gratifying or convenient?
But I have already answered that question.
The answer to "Why be Good?" is:
If I am someone who desires resurrected eternal life in Heaven; then no matter how often and badly I fail to live the Heavenly life during this earthly mortal life - I will never stop repenting my failures, and never cease from trying to live better; simply because a life in harmony with God's loving creation is the life I want, more than I want anything else.
H/T To David Earle for a comment that helped trigger this post.
