What is the KEY POINT in mind of an employer while selecting candidates for employment during interview?

The main thing they keep in mind is the requirement and objectives of their jobs and at the same time whether the person being selecting fulfill those requirements and objectives. 

It may be vary upon requirment and the nature of the company and profile required. Each and every job has a seperate profile, But the Employer want to see the ability, sincerity and confidence of the candidate for which he is going to hire.