Muslim is responsible to rectify himself and others as much as he can. Amr Bil Ma'roof and Nahi Anil Munkar is one of very important obligatory duties on every Muslim just like Namaz, fasting, Zakat, Khums, Hajj etc.
We must try our best to correct ourself and others as much as we can, but we have to be polite with others and never hurt their feelings. We have to have wisdom and good advice when calling people to the Way of Allah ( 16:125).
We are not allowed to be negative in front of wrong faith or wrong behaviour, because negative attitude can indirectly endorse or encourage wrong. We must try to do our best to help others and make them aware about the truth and never leave them indulging in wrong when we can help them. It is very important to do this responsibility with wisdom and good way of advice.
We respect every human being because Allah has granted honor to all human beings (17:70) and we feel for them and been ordered to help them as much as we can. Respecting others does not mean letting them do wrong, and accepting them does not mean accepting or endorsing the wrong.