What is the doctrine of the Malachi Catholic Church?

Answer 1

--Is Catholic--

I think you mean MELKITE Catholic Church. To learn about them, visit

http://www.melkite.org

Answer 2

Hiya,
I did not know there was a Malachi Catholic Church.

I found this in Wikipedia, hope it helps...
The last of the twelve minor prophets and the final book of the Christian Old Testament is commonly attributed to a prophet by the name of Malachi or Malachias.

The book of Malachi was written to correct the lax religious and social behaviour of the Israelites – particularly the priests – in post-exilic Jerusalem.