“Keep back Your servant also from presumptuous sins; (i.e. the sin of presumption) let them not have dominion over me. Then I shall be blameless, and I shall be innocent of great transgression.” Psalm 19:13 (NKJV)

Belief is a component of faith, but not necessarily faith!

One could believe a lie or one could presumptuously apply a truth to oneself without the authority to do so.

A good example of this:

Deut 1: 6,8 (NIV) “The Lord our God said to us … ‘See, I have given you this land.  Go in and take possession of the land that the Lord swore he would give.’”

The Israelis liked this word.  They patted themselves on the back that God had spoken to them.  The problem – they did not enter into it!

Then later, (and this is the point), a few presumptuous people finally came around to God’s command – a day late (Hebrews 3:13) and decided to take God at His Word.  Either they were not aware of God’s full council or they were deliberately and presumptively taking only what fit their religious thinking and so reaped the consequences of the sin of presumption. (Hebrews 3:11)

In short, they decided to “Go up and take the land” … but God was not telling them to do this.  Therefore, It was not faith, but rather a form of rebellion.  God dealt with this severely (Hebrews 4:1-3, 10).

Remember, let us keep firmly in view that these presumptuous people are doing what God said to do.  Only they are not doing it by faith, as they are choosing one word of God over another, ignoring the full council of the Lord.  They are acting as If the word of God were somehow detached from the timing of God, even detached and somehow separate from God Himself.