'Unbelief' in the Bible

But he did not doubt or waver in unbelief concerning the promise of God, but he grew strong and empowered by faith, giving glory to God,

That is true. They were broken off because of their unbelief, but you stand by your faith [as believers understanding the truth of Christ’s deity]. Do not be conceited, but [rather stand in great awe of God and] fear [Him];

for if God did not spare the natural branches [because of unbelief], He will not spare you either.

And even they [the unbelieving Jews], if they do not continue in their unbelief, will be grafted in; for God has the power to graft them in again.