Danger of Unbelief

Hebrews 3
16 For who were those who heard and yet rebelled? Was it not all those who left Egypt led by Moses? 17 And with whom was he provoked for forty years? Was it not with those who sinned, whose bodies fell in the wilderness? 18 And to whom did he swear that they would not enter his rest, but to those who were disobedient? 19 So we see that they were unable to enter because of unbelief.