Therefore, brothers, be all the more diligent to confirm your calling and election, for if you practice these qualities you will never fall. For in this way there will be richly provided for you an entrance into the eternal kingdom of our Lord and Savior Jesus Christ.
2 Peter 1:10-11
The solemn challenge in 10 is couched in the same terms as 5 and it is clear that, for Peter, the way to make sure is by 'doing' these things, that is, seeing that our faith is of the sort that expresses itself in these qualities. This does not mean that we are saved by our own efforts or good works, but it does insist that real faith always produces them, and that when they are absent, faith is absent too. This is the explanation of the disturbing emphasis Jesus lays on works in the parable of judgment in Matthew 25:31-46 - it is not that Jesus is teaching that we may be saved through doing works of goodness and mercy, for that would be to contradict His own teaching and the teaching of the Spirit through the apostles throughout the New Testament, but that the test of works will be applied to prove whether faith has been real. The words 'I was an hungered, and ye gave me meat….' and 'Inasmuch as ye have done it unto one of the least of these my brethren….' reveal quite simply and clearly that their faith was of the sort that expressed itself in brotherly-kindness and love, and consequently they made their calling and election sure, and thus, as Matthew 25:34 indicates, an abundant entrance into the everlasting kingdom of Christ was ministered unto them: 'Come ye blessed of My Father.' How wonderful, and how solemn!