First of all, why talk about god and nature let alone redefine them? We know from Žižek and other sources that neither god nor nature exists, although for different reasons and in different ways. For Žižek, god himself/herself becomes an atheist in Christianity by witnessing his/her own inexistence. Like god, nature also does not exist, but in a more radical way (it doesn’t even get to be a witness to its own inexistence). The common denominator of god and nature is that they sometimes function like a figure of big Other, which means that they have effects on the unconscious as the signifiers that they are, without really existing in a consistent manner. So if “god” and “nature” are just that, signifiers, why not redefine them as signifiers? My wager here is to redefine “god” and “nature” circularly by referring to each other so they can make sense without any of them taking up the role of a big Other.
Readers of Žižek are familiar to the notion of an exception grounding a universality. This notion is directly applicable to god and nature: God is the exception that grounds the universality of nature. God is an exception to nature, (s)he is not bound by natural laws, but precisely as an exception, (s)he grounds nature as a universality, (s)he gives nature meaning, e.g. the purpose to serve humanity etc. Without god, nature is a meaningless conglomeration of random things and events whose only apparent function is to selfishly reproduce themselves. And without nature, god cannot have a useful purpose. When god is stripped of nature, (s)he appears to be a useless agent, or worse, as an abusive monstrosity. 
Now we have a nice formula that links god to nature, but it’s insufficient by itself, because as we know from Žižek, the notion of an exception grounding a universality is a masculine notion. We also have to consider its feminine counterpart, or its feminine “limit” (in a mathematical sense) where All becomes non-All.
What happens when god ceases to be an exception to nature? Instead of a transcendent God above nature, we get an immanent god that dwells in nature. The masculine notion of God is a transcendent entity that embodies the purposes and meanings of nature; the feminine notion of god is a dispersed being that consists of the immanent embodiments of purposes and meanings of nature in natural entities. This operation makes nature non-All.
We would like to have a formulation that holds for both sexes. Let us formulate the pair god-nature as the displacement of another pair enjoyment-castration. In this way, we reach at a circular definition of god and nature that consists of two related statements:
A. God is the enjoyment of nature.
B. Nature is the castration of god.
A: God is the (either transcendent or immanent) embodiment of purposefulness and meaning in nature. But as we know from Žižek, this meaning and purposefulness is strictly correlative to an underlying purposeless non-meaning that we call enjoyment. Enjoyment is the inhuman excess that distinguishes humans from the rest of the nature, from plants and non-human animals. So it’s legitimate for us to call god the enjoyment of nature. In terms of signification, the difference that “god” introduces “nature” is a difference of enjoyment.
B: Nature is dependent on the word uttered by god. According to the Žižekian interpretation of Schelling, nature emerges from the word of god, with the transformation of the god of drives into a god of desire. But, as we know, this first word also brings alienation, and it brings symbolic castration. Since nature originates from the self-castration of god, we can call nature the castration of god. In terms of signification, the difference that “nature” introduces “god” is a difference of castration.
Now we have a self-referential formulation of god and nature that works for both sexes. Let’s see how:
In the masculine version, god as the enjoyment of nature takes the form of an exception that universalizes nature. When god appears as an exceptional enjoyment (purposelessness), nature appears as a universal exigency (purposefulness). In religion, God is supposed to have transcendent purposes that are inaccessible to us mere mortals, but in any case it’s made clear that God should enjoy and we should serve his/her (usually “his”) enjoyment, which is by definition purposeless. On the other hand, by universalizing nature, by being reduced to its exception, god is castrated by nature. The original sin and the fall from the paradise is also the fall of god himself/herself. Christianity stages the castration of god by nature in the crucifixion of the Christ.
In the feminine version, god as the enjoyment of nature is not a transcendent being that universalizes nature, but it is immanently dispersed into the nature like a godly enjoyment. The godliness still gives nature purpose and meaning (as in the masculine version), but the godly enjoyment does not oppose itself to a universal natural exigency. Instead, the natural exigencies are interwoven with godly enjoyments. This means that there are no absolute purposes and meanings, all purposes and meanings are reflexively defined and relatively realized. This situation changes the status of symbolic castration. We cannot speak of a single agent (God) being castrated by a single exigency (nature). Instead, castration is immanent to both god and nature, it is immanent to their intricate relation. In femininity, purposefulness (exigency) and purposelessness (enjoyment) get into an intricate relation and become inextricable. It’s like the superego injunction that gives enjoyment the form of an exigency (duty, obligation). 
Since we now know how the signifiers “god” and “nature” function in masculinity and femininity, we can now redefine masculinity and femininity in terms of god and nature.
A. Masculinity is god as exception to nature.
B. Femininity is how much god overlaps with nature.
1. Note that the formula does not work in the other direction: We cannot say “Nature is the exception that grounds the universality of god.” Although it’s possible to ground the universality of god by an exception that occurs in nature (like a miracle), this exception won’t be natural and it cannot be called “nature”.
2. See “Exigency and Enjoyment” by Işık Barış Fidaner