There are other inhabited planets?

Why not? What makes us so special that people consider that I be alone in this universe. Even religion talks about being outside of our world - eg.: Angels.

But to be taken into account that a lot of great distances (million billion light years) makes it impossible to interference between civilizations inhabited planets.

From a Christian point of view (according to some opinions), between humans and aliens would be a split gate, because the farmers are under the burden of sin (virus in the universe).