Considering that there will shortly be a one world religion that will rule the world, whose leader will be the antichrist. No, religion is not slowly dying, it is just morphing into a false form of Christianity.
It is commonly believed that the Catholic Church will head the one world religion until her usefulness has passed and the antichrist (who is Satan) takes over, being for starters that Rome, which is the home of the Catholic church, is known as the city on 7 hills. Read Revelation 17-18 King James Version for reference.
Considering:
Religion Adherents Percentage
Christianity 2.4 billion[3] 33.51%
Islam 1.6 billion[4] 22.32%
Secular[a]/Nonreligious
/Agnostic/Atheist ≤1.1 billion 15.35%
Hinduism 1.15 billion 16.06%
Chinese traditional religion[c] 394 million 5.50%
Buddhism 376 million 5.25%
Ethnic religions excluding some in separate categories 300 million 4.19%
African traditional religions 100 million 1.40%
Sikhism 30 million 0.32%
Spiritism 15 million 0.21%
Judaism 14 million 0.20%
Bahá'í 7.0 million 0.10%
Jainism 4.2 million 0.06%
Shinto 4.0 million 0.06%
Cao Dai 4.0 million 0.06%
I don't see what you mean by 1 world religion when there are so many with so many followers.