Matthew 28:19-20 - "Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world."
Jesus made one last statement of instruction to His followers, and it was for them to go out and win the world! As my hometown pastor always said, "We are to practice saturation evangelism - reaching every possible person, by every possible means, in every possible location and situation." This is the explanation for outreach.
Another pastor friend of mine says, "In outreach, we must remember that people are not always in a situation or circumstance that they are open to our teaching. In trying circumstances, you must EARN THE RIGHT TO BE HEARD." This is why the church provides practical help to the needy and those people who are struggling with life situations.