Shiva and Shakti are the supreme Gods of Hinduism. They represent two inner states of enlightenment which are pure awareness ( light ) and love. Shiva is that awareness and Shakti is the love which streams from the awareness of God- Self who is Shiva. Both are neutral in nature, they do not have good or bad attributes, because they are transcendental realities of inner illumination. Shiva and Shakti have two children, Ganesha and Murugan who also have a very important symbolism within the Hindu traditions.
Genesha is the birth of this union on the earthly planes, this is why he is the remover of obstacles, since when we realize our true nature, we are free from negativity and infliction of pain on others and self. Ganesha is pure love, he is the product of the divine union of Shiva and Shakti in the Bhuva Loka ( Earthly Plane ).
Murugan is the transcendental and astral union of the two, which gives ideas, esoteric and spiritual thoughts which can uplift human suffering and destroy all which is in the way of spiritual evolution. This is why he is regarded as a war God, but this war is metaphorical, it is a spiritual war against ignorance which separates us from being one with the divine.