relationship between religion and morality

The only thing that justifies the meaning of ethics is the religion. The only thing which gives morality its color is the religion. Ethics can only be understood within the divine mandate.The religion is the only pulse of the existence.Through religion we know the purpose of the existence and we know why we are here And what will happen after death And the meaning of the existence What is required of us to do in this existence Without religion, the entire world will turn into full blindness.  

Ibn al-Qayyim (may Allah have mercy on him) said: There is no way to attain happiness and success in this world and in the Hereafter except through following the messengers of Allah. There is no way to know what is good and what is evil in details except through their instructions. The satisfaction of Allah is only attained through their traditions. What is good of actions, words and manners is what they were sent with". 

The dark world is cursed except for what the sun of the message came upon, as Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said.

Without the messages, you do not know the purpose of existence, nor the meaning of good or its value.

Without the messages, the world will turn into a frightening absurdity.

Without the prophecies you are stellar waste, as Carl Sagan says, or an insect as Sartre says.

Prophecy is the only pulse of the existence, and without prophecy the finest inventions and desires turn into horror.

Without the religion, the world will be worthless
.

If you asked any atheist about any existential question such as: Why are we here in this world or what will happen after death?

He may either mock of your question or keep silent.