When it comes to the three feminine gods, the author seems to have used Wicca as his template, presenting them as the Maiden, the Mother and the Crone. These feminine forms are represented as life stages, but the masculine forms are presented in a different context. While the Father corresponds clearly to the Mother, the other two masculine figures are defined not by a life stage but by a skill: the Warrior and the Smith. The seventh deity, which is asexual, is the Stranger.
What I'd ask Martin is this: Was it his intent to reflect a sexist attitude in the world he created by suggesting that two of the male deities were defined by their work or skill set, while the three female deities were defined by entrenched societal roles?
It's long been my contention that there is, in fact, an archetypal threefold "god" who is the rough counterpart to the triple goddess and who, like her, can be found in numerous traditions: the youth, the father and the elder. In the ruling classes, these correspond to roughly to the prince-princess, the queen-king and the witch/wise woman-wizard/sage.
This isn't meant as a criticism of Martin. He's the author, it's his world, and he can set it up however he chooses. It's just an observation from someone who finds mythical archetypes fascinating and sees fantasy novels as one means they're often preserved in modern society.
Certainly, sexism was rampant during the medieval period that serves as a model for many fantasy tales, even if they don't take place in our historical past, and Martin's depiction of figures such as Cersei Lannister and Sansa Stark shows that women were expected to mind their place in much the same way under the social norms of the world he created. Arya Stark's independence was the exception, not the rule.
I have to wonder whether Martin was sending a nuanced message by creating goddesses who are defined by who they are and gods who are identified by what they do. Is it a subtle dig at our own society's tendency to define men according to tasks and women according to roles?
Or is that reading too much into it? One of the most important rules of literature is that the various elements of any fictional world must be consistent with the society as a whole. The sexism that seems to me inherent in the Faith of the Seven accurately reflects that of the Westeros society at large. Certainly, it need not be taken as any more than that.
But I'd still like to ask Martin the question.