How Do You Make Your Calling Sure - by Faith Alone, or by Faith and Works?

What does it mean to make one's calling and election sure?

St. Peter uses this phrase, "make your calling and election sure" in his 2nd epistle. He says:

2 Peter 1:4 Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust. 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. 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:

Reading that in context, what he means is that one can do things which will make their faith in God more perfect. Thus, giving a greater hope of salvation. Indeed, he says that if one is diligent in cultivating virtue in addition to faith, they will never fall.

Aren't those who are called and elected assured of salvation?

Apparently not. Otherwise, why would St. Peter recommend all these things which the elect must do in order to make certain that they do not fall away.

But I thought all you needed to be saved was faith alone?

Again, that is not what St. Peter is saying. He says that one must add to faith all manner of good works. And he condemns those who don't as people who are spiritually blind who have forgotten their vow to do good and avoid sin and thus to be saved.

We can also turn to St. Paul for more guidance on what one must do to be saved.

Romans 2:7 To them who by patient continuance in well doing seek for glory and honour and immortality, eternal life: 8 But unto them that are contentious, and do not obey the truth, but obey unrighteousness, indignation and wrath, 9 Tribulation and anguish, upon every soul of man that doeth evil, of the Jew first, and also of the Gentile; 10 But glory, honour, and peace, to every man that worketh good, to the Jew first, and also to the Gentile:
11 For there is no respect of persons with God. 12 For as many as have sinned without law shall also perish without law: and as many as have sinned in the law shall be judged by the law; 13 (For not the hearers of the law are just before God, but the doers of the law shall be justified.

And also:

Philippians 2:11 And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father. 12 Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling.

Conclusion:

Those who go by the false doctrine of Scripture alone claim that it is a sin to add anything to faith. But Scripture itself says that those who do not add to their faith all these virtues, are spiritually blind and will fall back into sinful habits.

Therefore, if you want to be saved, if you want to make your election sure, make sure to exercise your faith with works of charity. Because God only saves those who do His will.