So faith comes from hearing, and hearing through the word of Christ.
The gospel must be proclaimed for faith to truly exist on the earth. Faith comes by hearing. It is that clear. If the gospel is not preached, faith will not come and people will not be changed. It must be heard.
These days there is a lot of pressure for Christians to be involved in social action. I believe that such good works are a result of the gospel changing us. But they cannot really do what we hope them to do without the gospel. The gospel must attend our commitments to social change. We cannot end sex slavery, poor health conditions, water shortages, etc. on our own human power. Our own humanity got us into these messes!
The fact that the gospel has not attended recent cries for social action has created some really weird situations among Christians. We now have some "Christian gay rights activists". They have chosen to point out the evil of descriminatory prejudice while ignoring what the scriptures teach about homosexual practice. They conveniently ignore scriptural teaching on marriage to insist upon redefinition of marriage. But the gospel must address the entire issue, and not just the point that gets us social acceptance.
Christians should care about social issues. But we care with the gospel on our lips and in our hands. We know that hearing the word of Christ brings faith to some. And that faith in the gospel saves people who can then live the changed lives of the redeemed. The faith that comes by hearing is what the world needs most.