Philippians 2:12
So then, my dear ones, just as you people were always obedient [to my teaching] when I was there with you, so now, in my absence [also], be [obedient] all the more. [Continue to] complete your own salvation [i.e., by living faithfully to the end. See Rom. 13:11] with fear and trembling [i.e., with a reverent and submissive spirit],
Hebrews 4:1-2
So, as long as God's promise of entering into a state of rest with Him [still] remains, we should fear that someone among you will appear [in the end] to have fallen short of [attaining] it. [Note: In this section "entering into rest" refers to Israel entering Canaan (verses 6, 8) and to Christians entering heaven (verses 3, 9). The "Sabbath day rest" is represented as a type of both].
Hebrews 12:25
Pay careful attention so that you do not refuse [to hear] God when He speaks to you. [See verse 9]. For if those people [i.e., the Israelites] did not escape [judgment] when they refused [to hear] Him who warned them on earth [i.e., God speaking through Moses at Mount Sinai], how much less [likely] will we escape [judgment] if we reject Him who warns from heaven [i.e., Christ]?
Hebrews 12:28-29
Therefore, we should be grateful for receiving a kingdom that cannot be shaken [i.e., the church. See Col. 1:13; Rev. 1:6, 9]. So, with reverence and awe, we should serve God in a way that pleases Him,