We need to receive salvation by faith. Knowing that Christ died in our place and that God is willing to pardon our sins will not save us until we receive that pardon by faith. If a prisoner was condemned to die and was given a pardon, he would have to receive it in order to be set free. Saving faith is simply receiving God's pardon for sin. That pardon was secured by Christ's death on the cross.
Faith is the placing of one's trust in someone or something.
It is believing a chair will hold you up when you sit on it. It is believing the word or promise of someone when he gives it to you. Saving faith is believing in the promise of God. It is accepting the offer of salvation as a free gift from God to you personally. The Bible is the instrument of our faith.