I think, it is one-sided truth to hold that there were only differences, no similarities among religions. All types of religion have two aspects. There is, on the one hand, similarity among them on various matters, and, on the other, there are serious differences on some matters and insignificant ones on the other ones.

They all believe that human beings are finite, often do not live up to their full potential and may even do evil things. All serve to help humans to make contact with the spiritual Reality and thereby to lead better lives. In the process, all religions issue some of the same moral commandments, such as encouraging people to tell the truth, not to steal, not to murder, to work for peace in the world, and to be tolerant of others. That is another matter, some of their adherents follow these and some do not.

But it is also true that all religions do not have same world outlook. In this connection, we can take world's four largest religions, out of them three having faith in God, Parmatma, Allah and the fourth one too looking towards some super natural power:

Christianity holds that we are born sinful, that Christ, who is the Son of God, died for our sins, and that if we have faith in Him, we will go to heaven.

Islam teaches that we are born sinless and that we may go to heaven if we try our best to obey Allah. Islam even specifies that Christ is not the Son of God, and that He did not die for our sins.

Hinduism says that trying to get to heaven is a waste of time; even if we were to spend some time in heaven, we would eventually be reborn on earth, because we are trapped in a seemingly endless cycle of rebirth. The solution lies in Moksh only, which can get you reach the God and become one with Him.

Buddhism, though in agreement with Hinduism on rebirth, does not believe in God! It explains that the process of rebirth will continue until Nirvana is attained which means liberation from the consequences of one’s actions and being detached from them where you reach a state of bliss.

Obviously, if there are differences among religions, there are similarities too.