Love is a movement or attraction of an agent for an object which it perceives as being beneficial. When the movement is complete the object is - in some manner or other - united with the agent. However, the kind of "union" can vary hugely.
Food is united with feeder by its high-level form being destroyed and its material substance being assimilated.
Knowledge is united with learned by becoming integrated in their being without any loss to itself. The learner possesses the knowledge, but the knowledge looses non of its integrity by such possession and in fact gains power over its learner by directing their actions, subsequently.
The lover possesses the beloved - but only in the sense (if the love be wholesome) that they are motivated to care for and cherish and protect the object of their love as being precious to them.
The saint possesses God in the way that the learner possesses knowledge - but also by simply being intimately associated with God, in a communion and intercourse of being which results in the Eternal Life of the soul.