Actually you got your definitions mixed up. Ethics are culture-based, not morality. It is also ethical in some cultures to have sex with minors. Some people have even tried to make child porn legal in some countries.
Morality is based the the population you are with. It doesn't matter what Christian values say is moral, if a culture isolated from us thinks sex with minors is required for the child to grow up healthy then it is one of their moral values.
It was once considered moral to be homosexual. It was common practice by many cultures. With the rise of some religions, it became immoral in many cultures. Now in america, that tide is changing and only some religious groups consider homosexuality immoral. Drinking was also once considered immoral in the USA and a law was passed to make it illegal. Now it is a right of passage for teens entering college. Premarital sex, rock music, etc.
Take this quote from a website for example.
"Society has gone from Hollywood and television driving the moral standard, to Hollywood and television trying to keep up with society as a whole. Mass media now merely reflects the condition of society."
"Driving the moral standard", if the standard was from god, then there would be nothing to drive. Things would be blindly either moral or immoral. It would be unchangeable. We would not be concerned with things corrupting our children's morals. We care about these things because morality is learned and taught. It is a social construct of right and wrong, nothing more.
There are many places to look for your morals, your religion can give you morals (some religions say it is immoral to suffer someone of another religion to live), society can give you morals, and experience/reason can give you morals.
It is obvious that a religion wants you think believe morals come from their god/gods. This allows us to keep a strict set of rules over many generations and keep the church in power. This however is insular and refuses to look at all the other cultures as being acceptable. This is why they did not have problems killing, raping, and pillaging in the name of god. These people were immoral in their eyes.
When the spanish went on a rampage in south america, they did it because of gold and morals. Are we to say the natives were knowingly immoral? They acted in the confines of their own culture, but the rules of their gods who defined their morality. They were moral.
Morality changes with the times. It has changed in the last 50 years. Ethics also changes, just a bit more slowly.