Very good question.
Judaism, Islam, Hinduism, Voodoo, Spiritism, and all of the non christian religions are different forms of paganism, they do not believe in the one true God.
Roman Catholicism, Protestantism, Jehova Witnesses, and the rest of "christian" religions are different groups of heretics, meaning they have their own particular believes, different from those revealed to us by God. Even though they claim to be christians, they are worst than pagans, for they believe and preach a false christ.
The True Orthodox Church is the One Holy Catholic and Apostolic Church, where Christ is preached, and where sound doctrine is preserved unchanged.
In matters of faith and spirituality, you have nothing to learn from pagans and heretics, but in traditions, there are many things you can learn.
On the ground, in my day to day life, I get to know people from all over the world, with different religions, and I really enjoy talking to them, and learning their languages, their traditions, and what they believe.
For example, I know people from India, they are hinduists, and I learned many things from them. For example, to say hello, they put their hands together, at the level of their chests, make a gentle bow and say "namaste".
Namaste is usually translated as "hello", but it is not hello, it's a word with deep meaning, a way to show others absolute respect, something like saying "I see God in you".
As a christian, I know we are all created at image and resemblance of God, and we should respect each others, and I found that greeting very correct, like a bit of truth dropped among pagans, and I took it.
I like saying "namaste", bowing, and saying a little silent prayer in my head like "May Christ our God save you". Of course, I do this only with the indians, don't you think I'm flamboyant and go out there saying it to every single person.
You really have nothing to learn from a non christian and a heretical religion, and you can't be saved outside the True Orthodox Church, which is the One Holy Catholic and Apostolic Church.
But be not affraid, do not worry, our Lord and God Jesus Christ came to save us, and if you really want to be saved, He will take you to the One Church, which is the arc of salvation. Ask, and you'll receive, knock, and it will be opened. There is One God, One Saviour, One Church, and One path to salvation.