The greatest difficulty in answering this question is to give any effective meaning to the term "world ethics." Obviously, non-Christian ethical systems differ markedly from each other, and most of the points on which they all agree are also found in Christian doctrine. The Ten Commandments, for instance, are largely uncontroversial, and something like them, together with many of the other Old Testament prohibitions, can be found in most ethical and religious systems.
The most fertile ground for exploration would be to examine the moral teachings of Jesus Christ, particularly the paradoxical ones found in the Sermon on the Mount. The idea that you should love your enemy (Matthew 5:44) runs directly counter to every other major system of morals before Christianity. The title of Mary Whitlock Blundell's famous book on Ancient Greek codes of ethics, Helping Friends and Harming Enemies, gives a succinct description of the Greek view. However, the position is complicated by the fact that subsequent religious and ethical codes have been so heavily influenced by Christianity. Jesus Christ is regarded as an important prophet by Muslims, and the Quran contains verses based on those in the Sermon on the Mount, saying that one should love one's enemies. This should make it clear that "world ethics" do not exist, and that Christianity can most profitably be compared with contemporary or preceding systems, such as classical Greek or Roman ethics or secular humanism.