How are these terms related? simple : complex?

The terms are related in the sense that they are antonyms. Antonyms are words that mean the opposite of one another. An antonym of 'slow' is 'fast', an antonym of 'thick' is 'thin'. 

The definition of simple (basic, easy to understand, not complicated) is the opposite of the definition of complex (containing many facets, difficult to understand, complicated). 

There is nothing inherently wrong with being gay. speaking generally, opposition to gays are usually judged on people's moral basis whether it be religion, experience or other factors. to conclude, there is no objective answer to this question only subjective ones that rely on people's idea of what is right and wrong.