Speaking for myself, I am at hubpages because the Holy Spirit led me here and my writings are as He leads me to write. Whoever is drawn to my hubs, I believe the Lord sends for His purpose. Thus, if my writings are encouraging to believers (and the Lord knows we need it), it is for His glory. If, atheists, agnostics, etc., are drawn, it is still for His glory and purpose and for the “other’s” consideration.
Jesus did not go around seeking atheists, He just went about preaching the Good News of God and seekers of truth (which included some Publicans and sinners) were drawn to Him. God, through Jesus Christ, did not commission us to go to atheists, but into the world and preach, teach the Gospel. Seekers of truth will be drawn by God's power and new Christians will explore hubs they believe will help them mature in the faith. These are the ones most likely to benefit from Christian writings just as they were the ones who responded to Christ.
Furthermore, in addition to our supporting and encouraging each other as our Lord commanded, the followers of Christian hubs include not only mature Christians and theologians, but also many nominal Christians, Christians following false doctrines, those who are disguised as Christians, those who believe they are Christians but are not, those who just want to learn more about the faith, and baby Christians who need encouragement to grow beyond "baby food. There are far more individuals reading our hubs than those who leave a comment.
To my way of thinking, Christianity is brought into contempt, and Christians insulted, when it is forced upon those who have no appreciation for God’s truth and clearly do not desire it. As Jesus remarks in Matthew 7:6, the Word of God is too precious for that. Our zeal against sin must be guided by the common sense He endowed us with, and trying to persuade hardened scorners, to whom it will certainly have no beneficial affect can only result in exasperation and anger and damage the cause. God is not the Author of confusion.