2 Peter 1:10
Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
Peter exhorted his readers to confirm their calling and election. Election refers to God’s sovereign, eternal choice of individuals that belong to Him. Calling refers to God’s action in time by which the choice is made evident. Our election took place before the world was made, while our calling takes place when we are converted. We can’t make our calling and election more sure than they already are, as God’s purpose can never be changed, but we can confirm them by growing in likeness to Christ.