The teachings of Jesus focus on mercy, reconciliation and redemption; this recurring theme in the gospel message is invoked by the Catholic Church to oppose the death penalty. Church fathers such as Clement of Rome and Justin Martyr asserted that the taking of human life is incompatible with the gospel and exhorted Christians not to participate in capital punishment. The church's opposition to the death penalty declined after Christianity became the state religion of the Roman Empire. Augustine recognized the death penalty as a means of deterring the wicked and protecting the innocent. In the Middle Ages, Thomas Aquinas reaffirmed this position.