"Since Macedonian and Bulgarian are mutually intelligible, share many common linguistic features and are socio-historically related, some linguists are divided in their views of the two as separate languages or as a single pluricentric language."
Macedonian is language recognized in UN and in linguistic science.
Yes it is close to Bulgarian but also to Serbian and to all other Slavic languages, expecialy to Southern Slavic group. The reason for this is spread of Christianity between Slavic people, and historical circumstances.