The sin of bloodguiltiness...

"Millions are perishing today 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 empowered with God's Spirit. When we are brought face to face with this truth, our hearts will spontaneously cry out in contrition and shame. We will confess our sins. What sins? The sin of bloodguiltiness; the sin of disobedience; the sin of unbelief; the sin of selfishness and worldliness, grieving the Holy Spirit and quenching Christ's love and His kingdom. These sins will become a burden greater than we can bear, until we have laid them at our Lord's feet and seen Him remove them." (Andrew Murray, "The Key to the Missionary Problem" p.111)