To add a little context for those who might not be too up on modern church history: Andrew Fuller was an 18th-century Baptist minister, and one of the founders of the Baptist Missionary Society, which sent out his friend William Carey, the first English Baptist foreign missionary, to India.
He was also the author of a booklet titled The Gospel Worthy of All Acceptation, a polemic against the then-popular hyper-Calvinist denial of the duty of the sinner to repent and believe in Christ. Carey read it, and concluded that if all men have a duty to believe the Gospel, then there was a corresponding obligation upon Christians to bring the Gospel to all men.