5. And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge;
6. And to knowledge temperance; and to temperance patience; and to patience godliness;
7. And to godliness brotherly kindness; and to brotherly kindness charity.
8. For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.
This is how to make salvation fruitful, or how to make salvation work for the Glory of God and the increase of His kingdom. It is not that we have to actually DO anything. We have to add virtue to our faith, and add knowledge by studying and prayer. We have to develop temperance and patience. These things together form in us Godliness and brotherly kindness. And above all we need charity, or else we are become as sounding brass. Taken together these things make us helpful to others and witnesses for the kingdom of God. Or, in biblical terms, it makes us fruitful.
9. But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins.
10. Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
11. For so an entrance shall be ministered unto you abundantly into the everlasting kingdom of our Lord and Saviour Jesus Christ.