This is a statement that is often made in the same breath as “All religions lead to God,” or something similar. Atheists insist that all belief systems, save their own, are wrong. How inclusive and tolerant of them.
At any rate, there is some truth to the statement that all religions teach truths. For example, all belief systems including atheism state that murder is wrong - although atheists have no moral basis for claiming that murder is wrong. And atheist leaders of the 20th century proved that fact roughly 100 million times.
All religions and some atheists believe that greed and self-centeredness are wrong - although most of us live as though that isn’t true. Not to worry - we’re all hypocrites to one degree or another. Regardless, it is true that there are some similarities in all belief systems. On the other hand, there are at least two major problems with this statement.
First: In order to actually believe that all religions are basically the same, you have to ignore their most important and deeply held differences. For example, you can’t have one God (Christianity) and 5,000 gods (Hindu). You can’t have one God, Creator of but separate from His creation (Christian) and god the same as creation (pantheism). You can’t have one Creator God, personally involved in creation (Christian) and no god (Buddhism).
Atheists understand that this type of plurality does not and cannot exist and that is why atheists seek to do away with every belief system except their own.
Second: Where Christianity veers wildly off on its own is when it comes to the nature of a fulfilling life and salvation.
All other religions, including atheism demand that Jesus was not God in human form.
All other religions, including atheism conclude that the way to a fulfilling life and to ultimate salvation is through self-effort.
Jesus insists that we are only saved by grace through faith in the fact that Jesus is God the Son (“If you have seen Me, you have see Father God”) and in what He accomplished for us during His sacrificial death, burial and resurrection.