The quote is stating that God will reward him "who perseveres under trial," that is to the man who stands for what he believes, even in the face of opposition. God will give "the crown of life" to those who continue to love him when pressured to do otherwise.
Sir Thomas More was pressured to change his feelings, opinions, and official position regarding annulment of weddings consecrated by the Roman Catholic Church. King Henry VIII is seeking More's support of his petition to the Pope to have his marriage to Queen Catherine annulled so he can marry Anne Bolyn. More is approached and counseled to give his backing to this request by persons ranging from his wife to Cardinal Wolsey to King Henry himself.
In the face of all these influential individuals and arguments, More remains steadfast in his belief that the annulment, the breaking of the sacramental wedding vows, is immoral and refuses to change his position. He maintains to his death that, "The King is Supreme Head of the Church in England 'so far as the law of God allows'" despite considerable pressure, threat, and ridicule. Based on the quote from the Bible, More received his crown from God after he was executed by Henry.