In 2Peter 1:8-9 Peter points to the work of God on the one hand and the work of the believer on the other (cf. 1Peter 2:4-8). If the Gospel (the accurate knowledge, G1922 – epigenosis) of our Lord, Jesus, is believed and active in us, these things will abound and we won’t be idle in God’s hands or unfruitful in what we do for him (cf. Philippians 2:12). The word idle (G692) is used by Jesus in the Parable of the Householder (Matthew 20). In verses 3 and 6 the householder found laborers who stood idle (G692) in the marketplace, so he hired them and sent them into his vineyard. Peter’s point is that, if the believer applies himself to working out the things mentioned in 2Peter 1:5-7, he won’t be idle, because he will be laboring to produce the fruit of the Gospel, and he won’t be barren in producing fruit out of the accurate knowledge, (G1922 – epigenosis) of Christ, our Savior.
On the other hand, the believer who lacks the fruit mentioned in 2Peter 1:5-7, is spiritually near-sighted or unable to see anything that isn’t directly in front of him. (2Peter 1:9). This occurs when we are more concerned about our behavior or how we look to others. In the context of Peter’s epistle it concerns taking one’s eyes away from the Gospel and giving heed to heresy preached by false teachers. Put another way, it is taking one’s eyes off Jesus and placing them on himself. This, in effect, denies the Lord who has bought or redeemed us (2Peter 2:1-2). When we no longer look into the Gospel (2Corinthians 3:18), which is the only accurate knowledge of Jesus we have, we are no longer tasting that the Lord is good (1Peter 2:3), nor are we coming to that Living Stone (1Peter 2:4). Instead, we are standing with those who have rejected Christ as Savior (1Peter 2:7-8), and we no longer remember we have been purged of our past sins, or what life was like before our believing the Gospel (2Peter 1:9).
The vehicle through which the things mentioned in 2Peter 1:5-7 operate (2Peter 1:8) is the Gospel or the knowledge (epignosis – G1922) of our Lord, Jesus Christ. It is because of the Gospel that we are moved to be bold or ready (G703) to extol the praiseworthiness of God, and to reach out to know (G1108, gnosis) more about Jesus. Because of the Gospel (viz. epignosis – G1922), we take measures to so discipline (G1466) our behavior that, by looking into the mirror of the Gospel (2Corinthians 3:18), we become more and more like Jesus. Moreover, beholding the suffering of Jesus in the Gospel (the correct knowledge of our Savior), moves us to endure (G5281) the cost of being called his disciple.
These four characteristics operate on the inward man. The final three operate as a witness to others (cf. 2Peter 1:5-7). That is, understanding the Gospel or the correct knowledge (epignosis – G1922) of Christ moves us to publically acknowledge God in our devotion (eusebeia – G2150) to him. However, one cannot love God while despising his brother. Therefore, public devotion (eusebeia – G2150) to God moves the believer to publically identify himself with his brother in Christ through acts of kindness (philadelphia – G5360), especially during times of trial and persecution. All of these things cannot be kept secret, because one cannot be a secret follower of Jesus. By loving (agape – G26) the brethren, the world recognizes us as Jesus’ disciples (John 13:35).
Diligence (G4710) is expected on the part of the believer as he seeks to be fruitful in his walk with Christ (2Peter 1:5, 10). The Septuagint uses this Greek word 15 times, and it is usually translated with haste. In Romans 12:11 Paul writes that the believer’s business (G4710) for the Lord should not be slothful or irksome (grievous – G3636), so Peter tells us to be diligent or make hast (G4710) in adding these things in faith to our walk with Christ. If we do, then we can be assured that we will not fail in the work of God (cf. 2Peter 1:8-10).