There is no true identity for man without religion.
I actually agree with this, though it is phrased rather backwards. Identity is precisely what religion is about. The deep connections and attachments a person forms become
that person's religion. It becomes the glue that connects him to the world he lives in. It does not matter what those connections are. It does not matter if he believes in god or has an atheistic belief. What matters is that he has a belief, and it serves a function in his life. By virtue of that function his belief is religion, not by virtue of the belief itself.
Thus, lack of religion makes a person lacks true identity
Again, there is truth here, but all twisted. You can't live without relating to the issues of death, living, purpose etc. All the central themes of religion. A person's dealings with these issues through his life are his true religious activities. Worshiping entities is vanity.
So yes, if you do not have religion, you do not know who you are. But then finding your religion becomes a matter of finding out who you are. No dusty scroll can tell you that. Only living your life can.
Emmanuel Kant assures that identity is built on the basis of our relationship with others. But he didn't clarify its mechanism. Religion, however, organizes one's relationship with others, which means that religion is the basis of identity not others.
Kant speaks cleverly. We learn who we are in the community we live in through interaction with others. We step into roles, willingly and unwillingly. We adapt to what we interact with, whether it is other people or just things, and the total experience teaches us our identity. The are no permanent and never changing boundaries between minds.
Organized religion ignores this, and forces people to accept static roles that prevent them from growing and realizing their potential. This is not a good thing.
I am learning more and more who I am. Not because I'm reading ancient books and saying prayers by rote, but because I try to be mindful of the experience I have. I have come to realize that there are connections and attachments that are so subtle that words cannot grasp them. These are deep, universal truths everyone knows in their hearts. It is what life inevitably teaches us, simply by having the experience. But we can never speak of these truths. They become lies in our mouths. It is not forbidden to speak the name of god. It is impossible. You can hear it in your heart, but on your lips, it will be a lie.
It is strange, really, that ignoring everything anyone has ever told you about god is the only way to really come to know god. And this knowledge, as I said, can never be spoken. No matter how wise you are, the truths in your heart will be lies if you speak them.
But simultaneously, by knowing them in your heart, you will be able to hear them in the words of others. This is what some religious leaders make use of in manipulating their followers.