The mandate to care for the needy and the oppressed is thread woven throughout the entire fabric of scripture. Deuteronomy 15:7-11 informed the recently emancipated Israelites that they were responsible to care for the poor and needy. Many years later the prophets of the Old Testament repeatedly rebuked the people for putting on a religious show all the while social injustice was allowed to go unchecked. The prophets told the people that providing justice for the oppressed was as important as their "religious" practices. In Matthew 25:31-46, Jesus taught his followers that their love and care for him would be demonstrated by their love and care for others. In the epistle of James we are taught that faith without works is dead.
What good is it, my brothers, if someone says he has faith but does not have works? Can that faith save him? If a brother or sister is poorly clothed and lacking in daily food, and one of you says to them, “Go in peace, be warmed and filled,” without giving them the things needed for the body, what good is that? So also faith by itself, if it does not have works, is dead.
In other words, words alone are not enough. I was once told that we don't need to feed homeless people, we just need to teach them "how to believe." This kind of thinking flies in the face of James 2 and countless other scriptures that command us to provide for those in need. The gospel needs to be demonstrated; it needs to be lived out. To put it as simply as I know how, if Jesus is Lord then we must do what he commands and we have been commanded to care about social issues. If all we do is preach the Word then we are neglecting half of our job and we are deceiving ourselves.
On the other hand, however, if we think that we can really make any real and lasting social progress without preaching the gospel of Jesus Christ then we are just as deceived. When someone is a hungry they need to be fed. A free meal, however, will only fill an empty stomach for a few hours, but it will never forgive a person's sins. An emergency shelter can provide temporary protection from the elements, but it will never provide the everlasting hope of eternal life. Awareness campaigns for human trafficking may help rescue a few women and children, but they will never eliminate the problem so long as there are predators willing to exploit them for profit and perverts hoping to purchase them for pleasure. A new well in an African village may provide safe drinking water but it will never quench the thirst for righteousness. On their own, these "solutions" only temporarily treat symptoms but they will never address they root cause, a person's heart. The good news of Jesus Christ is the only true and lasting remedy for the ills of the world. We will make the greatest, longest lasting impact for the kingdom of God when the actions we take communicate the same message as the words we speak, when the gospel of Jesus Christ is served along with a plate of food or provided alongside a place to sleep or preached in tandem with calls for justice.