Yes.
Per Ephesians 2:8, it is, and per Hebrews 12:2 it was authored and finished for the believer by their Saviour, Jesus Christ.
Faith in Him as Saviour and Lord is not something that all men have per 2 Thessalonians 3:2, and it is the evidence of God's working in someone per Hebrews 11:1.
It is also a fruit of the Spirit per Galatians 5:22, so anyone who does not have the Spirit of God in them will never have or exhibit true faith, especially under trials and tribulations.
In Galatians 2:16-20 and other places it is said to be "of" ( by or from ) Jesus Christ,
while Philippians 1:29 makes it abundantly clear that the ability to believe is itself given to the Christian:
" For unto you it is given in the behalf of Christ, not only to believe on him, but also to suffer for his sake; "
Therefore, faith cannot exist as a requirement or condition that gains a person God's favor, but only as an evidence of His saving grace and His favor that He has placed upon them through no effort of their own.
Per the Scriptures, we are saved
by grace,
through faith...and
that not of ourselves, for it is the gift of God....
Again, not "of" ( by or from ) works, lest any man should boast.
God's
gifts completely rule out the possibility of boasting in anything that we did or had in order to secure something from the Lord's hands.
We as Christians do not rest on the fact that we have faith.
We rest on the fact that He has saved us and called us with an holy calling...which was
given to us in Christ Jesus before the world began ( 2 Timothy 1:9 ).
We do not rest on our works of righteousness ( like belief on His Son and faith towards Him ), but rather on the fact that it was
not by those works of righteousness which we have done ( Titus 3:4-7 ), but by His
mercy He saved any of us for Himself.
We also place our trust in what He has both given to us and accomplished
for us...
Eternal life with Him and His Son, that
includes salvation from His eternal wrath and judgment in the Lake of Fire.