Happiness is the purpose of all sentient beings, whether they realise it or not. There are two types of happiness: low-level happiness (based on material goods) and high-level happiness or spiritual happiness. The majority of people are seeking mainly the first type of happiness, but after accomplishing it they still feel something is missing, they realise that material satisfaction only is not enough to be truly happy. So, they start searching for real happiness. For that they take different paths: some of them start using drugs or alcohol (the best way to destroy themselves), other people choose spirituality, the inner development.
To reach a balanced state of mind and calmness, this must be the objective of a person who’s seeking true happiness. If one has full control over his/her thoughts and emotions, he/she can develop good relationships with other people and can be more effective in his/her activity. All major religious traditions promote the improvement of constructive emotions (patience, forgiveness, tolerance etc.) in spite of destructive emotions (hatred, anger, jealousy, extreme attachment etc.). So, in order to achieve happiness, we have to cultivate the constructive emotions and avoid destructive ones, irrespective of our faith, even atheists.