Everyone practices some kind of ethics. Atheists practice atheist ethics, Christians (should) practice Christian ethics, clowns practice clown ethics. A system of ethics is simply a standard of morals outlining good and bad behavior. Each ideology has its own code of ethics.
Secularists are forced to develop ethics from an atheistic or agnostic foundation. This is particularly difficult because having denied a central starting point for the entire concept of morals, they are left making arbitrary decisions as to what is good and what is bad. Religious people have a stronger basis for morality because they generally appeal to an authority outside themselves. Christians use the Bible and Church doctrine to defend their standard for behavior. A belief in absolute truth lays the groundwork for universal ethics, and even explains why many outside the faith attempt to live according to its principles.
The Christian standard for ethics is in the Bible. To defend against immorality and social chaos, we must be familiar with biblical teaching and able to defend our views in the public forum.