Hebrews 4.11 encourages us to strive to enter eternity so that no one misses it through disobedience.
Israel failed initially to enter then ultimately remain in the Promised Land because they disobeyed God. The first generation of recipients to inherit the Promised land whom God had rescued from slavery in Egypt, had no faith in God so were not allowed to enter the land He promised to give their forefathers. The next generation did receive the land but after many generations of disobedience was removed from their inheritance by godless nations.
Now God has come to us in Jesus Christ the Savior of the world and He too promises a rest, an eternal dwelling for all who place their trust in Him.
The author of Hebrews commands his adherents to strive to enter and remain in that rest – the promise of eternal life. While the Scriptures are clear that salvation comes by grace through faith it also is clear that men must repent from their sins, confess with their mouth Jesus is Lord and obey His commands as evidence of their salvation.
Thus we strive first by obeying God’s Word for we will give account for how we lived in obedience to that Word on that day when we face God at the threshold of our eternal rest.
Second we continue to confess Jesus as Savior and Lord both by our actions and our words. In this way we remain faithful, an encouragement to the brethren and a witness to the lost. Christians were first so named by pagans who heard the Name of Jesus repeatedly spoken from their lips.
Finally we strive by praying for grace and mercy individually and collectively.
While we are saved by the blood of Jesus we are daily being saved as we continue to wrestle individually and corporately against our flesh that is always in rebellion against the will and ways of God.
So then if we would make our salvation sure we will obey Scripture, confess Jesus to the world and pray regularly for God’s mercy.