Rebellion often simmered after Israel left Egypt and entered the wilderness. It came to full boil at Kadesh, when the Israelites refused to enter Canaan. That was “the rebellion” that warns us “today” (Hebrews 4:7).
Therefore, as the Holy Spirit says, “Today, if you hear His voice, do not harden your hearts as in the rebellion, on the day of testing in the wilderness, where your fathers put Me to the test and saw My works for forty years” (Hebrews 3:7-9 quoting Psalm 95:7-11).
Now, notice how the Spirit uses words about disobedience and unbelief interchangeably. Notice also how the Spirit applies this truth to Christian striving or effort.
And to whom did He swear that they would not enter His rest, but to those who were disobedient? So we see that they were unable to enter because of unbelief (Hebrews 3:18-19).
For we [Christians] who have believed enter that rest…. Those [Israelites] who formerly received the good news failed to enter because of disobedience…. Let us therefore strive to enter that rest, so that no one may fall by the same sort of disobedience (Hebrews 4:3, 6, 11).
They failed to enter the Promised Land because of disobedience…unbelief.
Yes, all of this applies to us. Jesus is the way to our Sabbath-rest. To enter is wholly a matter of faith, and God requires that faith to “strive” or as another version says, “make every effort.”