That which is Brahman is also Kali, the Mother, the Primal Energy. When inactive, It is called Brahman. Again, when creating, preserving, and destroying It is called Shakti.
Still water in an illustration of Brahman. The same water moving in waves, may be compared to Shakti or Kali.
What is the meaning of Kali? She who communes with Maha-Kala, the absolute, is Kali. She is formless and, again She has forms.
If you believe in the formless aspect, then meditate on Kali as that. If you meditate on any aspect of Hers with firm conviction, She will let you know Her true nature. Then you will realized that not merely does God exist, but He will come near you and talk to you, as I am talking to you. Have faith and you will achieve everything.
Sri Ramakrishna Paramahamsa
(Source: From the Foreword to Saundarya Lahari published by Ramakrishna Math, Page IX)