Faith is the believer's virtual way to communicate with God.

With faith and love in Christ Jesus, follow the example of sound doctrine that you learned from me.
2 Timothy 1:13 New International Version (NIV)

Faith is the door that leads to salvation, it is a personal commitment to God and a sign of gratitude for his sacrifice, Christ is the author and consumer of faith.

Set eyes on Jesus, the author and finisher of the faith, who for the joy set before him suffered the cross, belittling shame, and sat at the right hand of the throne of God.
Hebrews 12: 2 King James Version (RVR1960)

God endowed all men with a measure of faith and this is linked to the believer's grace and response to Christ, and this faith can increase as we maintain an intimate communion with God, based on prayer, reading the word. and gathering together.