Do you think that only English teachers can teach English or any one of any specialization and good in English can teach it?

I believe it has nothing to do with being an English graduate or an English teacher.
Teaching English needs you to be skillful in English first and then skillful in teaching as well..
This is the general rule.
But being an English teacher for specific fields (translation, literature, ...etc.) I think it needs a very expert teacher not just someone who knows English.
because English of daily life differs from the professional English.

I've been an English teacher for more than two years, I've taught it in language centers, in private classes and in Schools ....
But i'm not an English graduate !

Not only the English teachers, but the qualified English teachers are the ones to teach English.

I think any one of any specialization and good in English can teach it

from experience I can say that ,talent plays big part in tutoring

If you know the teaching methods and have a good English along with willingness to learn side by side you will definitely enjoy teaching English. Rather I would like to say that you may prove yourself a better one than a qualified English Teacher.

All is subjective to the level and type of English courses being taught. If you have a general English course for lower level students to teach, any native English speaker can teach provided that he or she has the required teaching skills for it. If ever it is for higher levels of English and for subjects such as English Poetry or Literature, then it would be better to have someone who has studied such fields extensively and is graduated in it. Having separate teachers for each type of level also helps in keeping the level of english taught manageable for a student...especially for those whose primary language is totally different to the vocabulary, grammar and phonetics of English.

 

But what is most important, is the teaching skills and wanting to teach. Without these two, you may be a PhD holder in any field and you still will never be fit to teach any level of any class.

There are basically two forms of English:  Colloquial and Formal (grammatical), the former being day to day English (conversational) and can be strongly influenced by region, dialect, slang etc. The second is grammatically correct English, sometimes referred to as the Queen's English and would be used in business, writing letters, composing CV's etc. Formal English would be used in TEFL as it is the basis for learning the language "properly", Colloquial English is generally "picked up" by mixing with native english speakers.

I have no qualifications to teach english but as a native english speaker and a former military Instructor, I am very confident in my ability to teach the subject, both "Formally" and "Colloquially".

Each subject or learning area has its technicalities and language. I speak good English but that does not necessarily make me someone that can teach English,. But, if I can learn the technical skills and didactics that go along with teaching English and develop passion for it then, may be, yes anyone can teach English.

your skills matter alot.
not all English qualified are good teachers.
I myself am a student of Economics but have been teaching English....& quite effectively i guess :D being a learning experience for me too.

From my experience and others' I do agree with Sema Farhoud.

In the issue of teaching, talent plays a big part, and I'm for the saying: Teacher are born; they are not created! Thus, I can say that a person from any discipline can teach a language well if he understands its features and measures, provided he is talented in the teaching process.