Reference

Galatians 6:8

For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting.
6

Let him that is taught in the word communicate unto him that teacheth in all good things.

7

Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap.

8

For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting.

9

And let us not be weary in well doing: for in due season we shall reap, if we faint not.

10

As we have therefore opportunity, let us do good unto all men, especially unto them who are of the household of faith.

Counter-Arguments

The strongest case that this verse does not belong in this theme.

Inherent Immortality

The verse contrasts "reaping corruption" with "reaping life everlasting," but it doesn't explicitly state that the soul or spirit is naturally immortal. Instead, it describes a consequence of actions (sowing to the Spirit leads to everlasting life), rather than an inherent quality of the soul itself.