There's lots of EASY ways to answer this... However, they are tongue and cheek.
An easy answer would be "because we aren't listening".
So I'll just tell you, I don't know. I only have theory.
I believe God created us here on Earth so that we could decide whether or not we go to heaven or hell. If we are saved or die the 2nd death...
Being so direct would eradicate the diversity of it all. From rich, poor, variance of colors, customs, etc. Where would we all be if God came down and made a major announcement so the entire world would witness? We wouldn't have much of a choice but to follow him then. We really would not have freewill after the world witnessed such an event.
I think it has to do with freewill.
I deal with your question a lot. I do not believe at all you have to be Eastern Orthodox to be saved either - I really don't even think it increases your chances of it. I believe mostly it has to do with how much you followed God's will. For example, I had a great grandmother who died 12 years ago. She was a WONDERFUL person, and southern baptist. She was dedicated in her faith, often quoted scripture, was a matriarch of the family. She made wonderful homemade pies. She loved her husband of 65 years dearly, the last 12 of which she took care of him and bathed him daily. Then she held bible studies with all the old ladies in the community every Monday and Thursday night.
On Sundays they would bombard their church with a lot of food. She was always there and was very generous to people. Charitable.
I don't know if she was baptized by triple immersion.
I do not know if she ever recited the creed, venerated icons, or had the Eucharist as we know it.
I do not know if she ever went to confession.
If she was to go to hell for her wonderful life, most of us are doomed.... I know I would be.
Anyway, I think God wants to see what we do to find him... To yearn for him...
Something like that anyway.