The formless and the form are two sides of One Reality. Everywhere we find them intertwined. Every object that has a form has a formless side to it. What is meant by this formless side is not absence of anything but the forces and energies that build the form and the state of consciousness of which the form is an expression.
Thus when it said that the Divine is formless it means that He can be felt and experienced as tremendous Power of different kinds or as qualities such as benevolence, compassion, love, wisdom or else as a state of Supreme Consciousness such as an absolute of Peace and Bliss or even at the very highest a Consciousness that surpasses even our possibility of experience, hence it is sometimes referred to as Nothing or Nothingness since the human mind with its limited instruments cannot really experience many things, let alone experience the Divine. Knowing this limitation and difficulty of humanity (which is nevertheless destined to be the bridge between the creation and the Creator) the Divine reaches out to us as the Mother, assumes Form and Name, even takes a human birth to keep the flame of seeking for God alive. When we see someone like us walking and arriving we feel enthused and inspired. Besides by assuming a human form, the Ineffable Supreme Mystery comes within the range of our senses and thereby a door easily accessible to us. We can then meditate not only on Her Name but also on the Form, the human Form of the Divine making everything so much easier.
Once we understand this it is not difficult to see why it is impossible for the human mind to discover the Divine by its own unaided effort. That is why one has to surrender to the Grace. But the rational mind and the ego, self-constructed with its help find it difficult to surrender since they think it is the end of precious individuality. However with time, persistent effort and above all Grace all these difficulties get resolved. What is needed is to persist and to persevere, to hold on and to hold out, to have faith and endure in the process with patience.
Loving regards,
alok
