The greatest need is prayer.

"The history of the Church demonstrates beyond question that the most important human factor in the evangelism of the world is prayer. The greatest need of the present hour is prayer. In our work at home and abroad we are placing more and more dependence upon men, machinery, and methods, and less and less upon God...What is needed above everything else today is prayer, true prayer, prayer in the power of the Holy Ghost, and prayer that meets the conditions of prevailing prayer so plainly laid down in the Word of God." ~R. A. Torrey: Chapter 53 of The Fundamentals

They can't be believed.

"When you’re busy hating everybody and denouncing everybody and seeking political solutions to everything it’s very difficult to evangelize, isn’t it? It’s very hard to be compassionate, to look on the crowds as though they’re sheep without a shepherd...I think one of the Devil’s tactics with respect to the church on the right today is to make them so hate everybody else that at the end of the day they can’t be believed anywhere, not even in the proclamation of the gospel."
~Don Carson: How to Destroy Evangelism with Political Animosity

Obsessed with Father

Jesus spoke often about His Father. We could say that He was obsessed with talking about His Father. Jesus spoke about 25,000 recorded words in the NT. He referred to His Father 181 times. At an average speaking rate (140 words per minute), Jesus spoke of His Father once every minute on average. How often do you speak of your Heavenly Father? Bring Him up in every conversation today. :) (John 5:17-47)

I told you to go.

"Those who never heard...the message of salvation...will look to us [on the final judgment day] with forlorn reconciliation to their fate, and that look will say, 'You knew! But you never came and told us; we never had an opportunity to know.' But sadder still will be the eyes of our Lord. In one of those paradoxes of the Christian faith, even as He receives us with joy, His heart will be broken over the multitudes who never knew He died for them. I believe His eyes will meetours much as they did Peter's on that night of denial, and without a word will communicate, 'I told you to go. I promised you My power. I assured you of My grace, but you chose to stay at home, to hold on to your comfort and security and were unwilling to go that my kingdom could be extended to the ends of the earth.'" (To the Ends of the Earth by Jerry Rankin, pages 55-56)

The Greatest Need

"The history of the Church demonstrates beyond question that the most important human factor in the evangelism of the world is prayer. The greatest need of the present hour is prayer. In our work at home and abroad we are placing more and more dependence upon men, machinery, and methods, and less and less upon God...What is needed above everything else today is prayer, true prayer, prayer in the power of the Holy Ghost, and prayer that meets the conditions of prevailing prayer so plainly laid down in the Word of God." ~R. A. Torrey: Chapter 53 of The Fundamentals

He Himself is the Power!

Hudson Taylor: We are a supernatural people, born again by a supernatural birth, kept by a supernatural power, sustained by a supernatural food, taught by a supernatural Teacher from a supernatural book. We are led by a supernatural Captain in right paths to assured victories. The risen Saviour, ere He ascended on high, said to His disciples, "Ye shall receive power when the Holy Ghost is come upon you."Not many days after this, in answer to united and continued prayer, the Holy Ghost did come upon them, and they were all filled. Praise God, He remains with us still. The power given is not a gift from the Holy Ghost. He Himself is the power.

The Sin of Disobedience

Millions are perishing to-day without the knowledge of Christ, and will go on perishing, simply because the Church is not doing the work for which she was redeemed and endowed with God's Spirit...When we realize there is so much work that has not been done for no reason than that the Church was not what she ought to be...Our hearts will spontaneously cry out in humiliation and shame, and make confession of our sin. The sin of blood-guiltiness; the sin of disobedience; the sin of unbelief; the sin of selfishness and worldliness, grieving the Holy Spirit and quenching Christ's love in our hearts, for His love and His kingdom these sins will become a burden greater then we can bear, until we have laid them at our Lord's feet and had them removed by Him. ~Andrew Murray from "The Key to the Missionary Problem"