What Should Christians Do?
Christ- First, last and foremost, making sure that you have the pardon Jesus died to give you should be uppermost in your thinking. How strong is your relationship with Him? How often do you read His Word? Is your Christian witness being carried out in your personal life or is your lifestyle indistinguishable from non-believers? This is something you cannot afford to get wrong so before you can worry about anything else, you need to make sure that you are right with the King of Kings.
Witness- This isn't just a good idea, it's our mandate as believers. God's ideal will is for NO ONE, not one single soul, to ever be condemned. Knowing that and knowing that hundreds of thousands, if not millions, of people in America alone need our help, what justification do you think we'll have when we stand before the judgement seat of Christ? There are several websites which can help you improve your delivery of the Gospel message. Before you know it, you'll be able to present the Good News in about ten or fifteen minutes. My experience with this is that after a while, it becomes so easy that you start thinking of it as a game (in a good way). The Holy Spirit will enable those who wish to share the Gospel so you don't have to worry about your lack of articulate speaking skills.
Missionary Work- If you are not able to participate in missionary work for whatever reason, I can well understand. I myself work a job that wouldn't be available to me anymore if I left for a month for a missionary assignment overseas. It is, however, a critical assignment and my personal belief is that if you're not doing it yourself, you should likely consider contributing money or supplies to those who are. If Americans are badly in need of Christ, we can say we at least live in a nominally Christian nation filled to overflowing with churches and Christian literature and television programming. People in third world nations are not so fortunate.
Tithe and Participation- Enabling your local church to carry out food and clothing drives as well as pay their employees who organize volunteer work is something you'll never regret. Likewise, contributing your blood donations and time to such activities will, if nothing else, leave you with the assurance that you are making a difference in peoples lives. Maybe your church is having a co-op with Habitat For Humanity and they need people to help with constructing houses for those less fortunate. Or perhaps the church will sponsor missionaries for trips overseas doing expensive (and potentially dangerous!) work. There are no shortage of options. For as pitiful as it may be, I assist with different programs in my own church.
I'm by no means perfect (or even very good, for that
matter) but recently I took over the podcast duties so that each week I play some small part in helping people learn about the word of God from my pastor, whom I consider to be a true teacher of God.
These are all small yet worthwhile things you, as a messenger of Christ, can do which are badly needed and can contribute to people coming to know Jesus as Savior. You may personally never convert a single soul, but if you enable (by any means) others to do so, trust me you'll never regret it. There's always more work to be done so don't think there's not enough to go around.