Without religion telling us what is right and wrong, what reason do we have to be moral? What is there to tell us what is right or wrong? Why help others when you can help yourself? Why be kind to others when you don't need to? These are the questions many face in life and eventually don't care about because they have no moral basis to follow.
The claim that religion is the sole basis for morals and ethics is only rooted in religion's popularity, nothing more. Ethics are of human origin (as is religion, in my view, but regardless). I believe humans gradually evolved to learn what was best for their society, and adopted those findings as societal guidelines, or morals. For example, the human race learned long ago killing fellow human beings probably was not very efficient for the development of their society, so they rejected it. They decided it was in their own interest to not kill their own kind. And it went on from there. We have to realize that just because all of us (or almost all of us) accept morals as effective guidelines for society does not mean it must have come from a higher source.
"Yes" in the sense that historically religion has been the strongest foundation or motivator for morality. And "no" in the sense that I do not believe religion or God is the only logical ground or justification for ethics. People do not necessarily need religion to know that certain acts are inherently immoral.
This is one of the greatest myths out there. Religion does not create morality unless it was absent in the first place. That is the logic of Colonialism and the Slave Trade. It is nonsense in the extreme to suggest that religion induces morality. Neanderthal man looked after its ageing parents without the help of Holy Water.