1 Peter 1:13–21 (NKJV)
In response to the living hope of the gospel, Peter moves in this passage to a discussion of the appropriate response to such a great hope. He calls the believer to take the commitment to God seriously, and to conduct oneself in the fear of the Lord. He basically tells the reader to get his or her mind right.
13 Therefore gird up the loins of your mind, be sober, and rest your hope fully upon the grace that is to be brought to you at the revelation of Jesus Christ; 14 as obedient children, not conforming yourselves to the former lusts, as in your ignorance; 15 but as He who called you is holy, you also be holy in all your conduct, 16 because it is written, “Be holy, for I am holy.”1 Peter 1:13-16
When Peter says “gird up the loins of your mind,” it is as if he is saying that the Christian should tighten up in order to run and fight without interference from other competing things. An ungirded , or loose, article of clothing would perhaps cause a runner or fighter to be caught on something while fighting or else to trip over the loose clothing while running. If someone tightens up the mind, refusing and rejecting thoughts that could get in the way of efficient and right thinking, then they can run the race without distraction. He continues with an admonition to be sober, or live with great clarity and focus. He further encourages the believer to rest on the grace found in the revelation of Jesus Christ. Believers should operate as obedient children, not being drawn away by lusts that controlled them during their times of ignorance. He gives a further level of encouragement as he calls the believer to be holy as God is holy. God’s holiness is the motivation for the Christian to be holy in conduct. God specifically calls the believer to respond to Him and to “Be holy, for I am holy.” This is a quote from Leviticus 11:44 and other references in Leviticus, where the Israelites were called to a life of holiness in response to the great holiness of Jehovah
17 And if you call on the Father, who without partiality judges according to each one’s work, conduct yourselves throughout the time of your stay here in fear; 18 knowing that you were not redeemed with corruptible things, like silver or gold, from your aimless conduct received by tradition from your fathers, 19 but with the precious blood of Christ, as of a lamb without blemish and without spot. 20 He indeed was foreordained before the foundation of the world, but was manifest in these last times for you 21 who through Him believe in God, who raised Him from the dead and gave Him glory, so that your faith and hope are in God.1 Peter 1:17-21
In this section of the passage, Peter alludes to the need for fear in addition to holiness. Fear is an extreme word in today’s vocabulary, indicating fearfulness or anxiety. While there would be an element of that if in the express presence of God, the normal understanding of fear in the life of a believer would be more akin to awe and reverence for God. One cannot trifle with God, for He is a holy, righteous God who will one day judge all of mankind. However, He does not necessarily look for Christians to live in a trembling mass of anxiety, wondering when judgment may fall from the heavens. Instead, God, I believe, is looking for people who will frame their thoughts, actions, and attitudes with the awe or reverence for God that He deserves. Live in a way that glorifies Him, and does not only satisfy you. The price paid for our salvation does not simply require adherence to a tradition that is now futile, but rather requires an appreciation for the sacrifice of Jesus Christ. His precious blood paid the price for our salvation, like a lamb without flaw, offered to God in our place. This Jewish imagery simply paints a picture for those familiar with the Levitical practice of animal sacrifice by pointing out that Christ was the better sacrifice. He was ordained before the foundation of the world, but was manifested in the latter times for us. If we believe in God, who raised Him from the dead and gave Him glory, then our faith and hope are justified, for they are in God and not in another human being or even in ourselves. The only path to salvation is through faith in Jesus Christ, the vicarious sacrificial lamb who was slain for my sins and your sins. So, gird up your mind and serve the Lord in holiness and fear, for He is worthy!