One of the greatness of Heaven or God as more commonly denoted in West is that Heaven provides one road too many for those who want to be in tune with Heaven even before they are due.
But men being man are always trying to be one up even above Heaven. Just because God is silent and men are noisy, there will be many voices proclaiming their religion or sect is right and all others not so. If it is true, then there should be only one religion and no sects in that religion.
We need to know God and Heaven better. There will always be more than one of every entity in nature and the universe.
There are many universes and we have the concept of multiple universes. There are not just one Sun but many. On Earth, there is not one race of humans but many.
But when it comes to religion, the narrow mindedness of some men may make them proclaim that there is only one Heaven, one Earth and one Hell. But surely there are many Heavens or levels of Heaven. There are more than one Earth-like planets and on Earth, there are more than one country.
There is always diversity and this is the reality. Diversity will not create chaos or disorder but in fact enables oneness and richness. We can say we are spoilt for choice, be it in religion or for that matter any entity.
Men may belong to one religion but they are not at odds with men in other religions. All religions are based on same Divinity and the need to enlighten and purify souls. The roads are many but as in the days of the Roman Empire, "all roads they say will lead to Rome."
God gives men many choices in everything in life. Men are blessed with freewill and men will ever be that spoilt for choice. Men of religions may end up in same Heaven but perhaps in different sectors or levels of Heaven, just as men on earth find themselves in different countries on Earth.
The above write-up is consistent with the Four Pillar Doctrine explained by Lord Bo Tien. God or Divinity is one but religions are many. All are one in God or Divinity. There may be diversity like the yin and yang. They may appear or seem at odds but when taken together, they complement and make one whole.
Yin and yang is like night and day of Earth. But the night Earth and the day Earth make one whole as well.