There are two primary groups.
One hears the gospel, builds faith on it and understand. He is like the good soil.
Matthew 13:23 he that received seed into the good ground is he that heareth the word, and understandeth it; which also beareth fruit, and bringeth forth, some an hundredfold, some sixty, some thirty.
Another group hears the gospel, but do not build faith on it and do not understand. He is like the hard ground of the way side.
Matthew 13:19 When any one heareth the word of the kingdom, and understandeth it not, then cometh the wicked one, and catcheth away that which was sown in his heart. This is he which received seed by the way side.
But imagine if there were no seed at all, no gospel, no word of God?
Therefore, faith comes from hearing, and hearing from the word of God.
Now faith is the gift of God (Ephesians 2:8), grace and the Holy Spirit are also the gifts of God. But the gospel, which is the word, which is really Jesus Himself, is the seed and root of all.