Spirituality does not necessarily mean being religious. Being spiritual means to approach life in a non-materialistic manner to understand the divine reality. For example, a typical spiritual person may seek to understand the purpose of the existence, life, and the real identity of the self; may ask 'Who Am I?'; may seek to comprehend the relation between time, space and the basic consciousness/perception of the seeker's self.
Spiritual intelligence is a form of intelligence like analytical and emotional intelligence. It can be cultivated provided one lets the seed of the spirituality to grow inside. When one allows the space for spiritual intelligence inside, their intuitive capabilities grow sharper and takes one more and more closer to eternal bliss and happiness.
There are many approaches and beliefs and claims of being spiritual. One may cultivate keen listening of their own voices to see if a specific approach takes them more closer to reality, happiness and clarity without being biased by the number of followers or popularity of specific approach. One should also be open to listen and understand and even try different approaches, if needed.
A spiritually mature (or enlightened or whatever) person is in peace with the self yet very alert without traces of laziness, complete acceptance of reality yet full of energy to improve things.
