Questions about morality will never have an agreed response and will always be the cause of wars, trouble and death. Saying all that, death, wars and trouble have their good side too.
If a child grew up in a war-torn country such as Syria, killing won't be as bad as those in peaceful countries put it. If another grew up in a family where the parents lied all times, lies will be the right thing. It's just life that we do not understand.
That said, every man, woman and child on planet earth develops a conscience of what is good or bad, right or wrong, et cetera. Our conscience creates a big difference from one person to another and differs completely based on experience, age and intellect. We become similar to animals who share one common language but differ in ways of thinking. In the end, we come to judge one another based on our own standards which do not apply to the worlds of those outside it.
So wars become a part of us, man-made, corrupt and lying beggars are elected as leaders, man-made, education makes us rigid to change and adaptation and finally the human race becomes uncouth, unfriendly and not admirable. We sort out the trash to find those of similar mindset and make them our allies. Those of a different school of thought are only filling up the world.
Hence the question about morals is actually the question about our different schools of thought. There is no such thing as universal truth, as universal belief, as common good for all, et cetera. The only existing laws concerning the subjects mentioned above are for the satisfaction of individuals on the merits of others without their consent but only little mind control, otherwise stated as manipulation.
Common and universal are terms intended to make everyone think that equality exists while it doesn't. They are words intended to drive the whole world unanimously to doing something even if a few individuals feel it doesn't suit them. It is a way of driving people into someone's own benefits.
"Morals are never universal. They are different, from different people and will always differ. We should never judge or criticize anyone based on what they believe; they may be right in their own world and wrong on ours." ~ Unknown