Qualities

For if these qualities are yours and are increasing, they render you neither useless nor unfruitful in the true knowledge of our Lord Jesus Christ. For he who lacks these qualities is blind or short-sighted, having forgotten his purification from his former sins. Therefore, brethren, be all the more diligent to make certain about His calling and choosing you; for as long as you practice these things, you will never stumble 2 Peter 1:8-10

"These qualities" : faith, virtue, knowledge, self-control, perseverance, godliness, brotherly kindness and (agape) love. The qualities we are admonished to cultivate in vss 5-7. These qualities result in rewardable production for the Kingdom of God. Sometimes those who have been cleansed forget Whose they are and what they've been saved from. That is a tragedy, for it neutralizes their testimony. The more we know about our Lord, the more we love Him. The more we know and love Him, the more we will demonstrate Him to the world. Systematic Theology, aka categorical Bible doctrine, stored in the soul, gives us ongoing, intimate knowledge of Who and What our Savior is, and what He expects of us. Like you know your husband. Like you know your lover. Like you know your best friend. It is a daily relationship, an ever-deepening friendship, with the One Who has given everything He is for you. Our daily relationship with the Lover of our souls gives us certainty, assurance, STABILITY in every aspect of life. Learning Him, loving Him, knowing Him, keeping steady company with Him, we will never stumble, because He holds us up in the face of all attackers (Jude 24). There's your confidence. IN HIM.