So you want to do your part in fulfilling the great commission? And the Internet looks like the mission field for you. Well here are a few of the things I've learned while proclaiming Christ in cyberspace.
Love the Person
This isn't a game. There is a real person on the other end of your conversation. Love them. Regardless of their lifestyle and actions, they bear the image of our God, by whom they were created and are worthy of dignity and respect. I can assure you, they are no worse a sinner deserving of death and hell, than you were before you were cleansed (1 Corinthians 6:11). Never forget the grace and mercy by which God saved you.(Titus 3:5) You didn't deserve it.(Ephesians 2:8-9) So don't expect them to either.
Preach the Gospel
This seems like a given, right? You know you need to give the Gospel, but often the unbeliever will skillfully lead the conversation away into debates over archeology, geology, psychology, and every other -ology, they think they have the facts to beat you with. Often, the conversation will start in one these areas, but you must quickly bring in the spiritual understanding of the issue and how it is redeemed in Christ. If you wait for a time when it won't be as awkward, it will never come. Our God has redeemed us in the blood of his own Son (Ephesians 1:7), and clothed us in his perfect righteousness. This will most likely seem strange and possibly uncomfortable at times, and sin and condemnation won't rate high on their list of likes either, but this is all part of the Gospel. We must not be ashamed of it.(Romans 1:16) It is the power of God for salvation.
You must be willing to lose: This isn't about you
Just as John the Baptist said that Christ must increase and I must decrease.(John 3:30) You too must be willing to get out of the way for God to work. Our job is to present the truth, not to make them believe it. This means our goal is never to "win" an argument. There is no room for pride in this mission. Saving face and having the last word, only serves self and not the kingdom of God. More often than not, you will have to step away from the discussion when continuing would only hinder the convicting work of the Holy Spirit, by hardening the heart of the one you are trying to reach, and bringing too much focus on you the messenger, as opposed to the message. This isn't "us" against "them." This is God's battle. Don't over step your bounds.
Yes, in the eyes of the world, this is losing. Don't be surprised by a response of gloating or attempts to provoke you into a heated argument. It only takes a few rash words to damage your testimony and prove "that you're no better than them." Remember, though it may seem as though your words fell on deaf ears, God's word does not fail (Isaiah 55:11) and the Holy Spirit often speaks loudest after we stop.