Here’s a down and dirty philosophy lesson. The next time anyone tells you there is no such thing as universal morality, ask them whether or not they believe they have a right to their own free will: to the thoughts in their heads. If they say no, you are dealing with an unstable person, be careful. But the average person will instinctively recognize that no one has control over your thoughts, your will – not even the Creator.
Next, ask them whether or not they believe that they have a right to those most basic things necessary to sustain and exercise that right to their free will, such as their life and their body. Again, the average person will admit to an instinctive understanding that they own their body and life.
If they will grant this, you’ve won the point. If we all have a right to our free will, our life and our body, all NATURAL RIGHTS follow from there through reason. THIS establishes a universal morality in terms of how we interact with each other in respect to other peoples’ natural rights. The difference in how different societies exhibit this recognition of universal morality is best defined as culture, not a different sense of morality.
And with that, you have not only established the irrefutable existence of universal morality, you have exposed yet another failure of language (the use of the word morality where the word culture should be used), you have also provided a strong inference to the necessity for a Creator (but that is a different post).