How does feminism go about making an inclusive space that's safe for victims of religion while also being open and inviting to the religious.
Well, I don't know
"Feminism" is a diverse and diffuse enough movement and collection of views that I'm not sure it makes sense to talk about this monolithically, but I think the roughly correct but uninteresting answer is "thoughtfully...".
I think there are times when stridently anti-religious views should be welcomed (say from Marxist feminists), and other contexts where it makes sense to avoid those arguments in order to make more room for people from various religious traditions to collaborate comfortably. There doesn't have to be only one acceptable kind of feminist space.
Also, disagreements can be productive. I don't think "an inclusive space" should preclude exposure to disagreement, even very strong disagreements on core beliefs. But disagreements can be discussed in a thoughtful way, where everyone is allowed to express themselves. Inclusion is about basic respect, and a commitment to multi-culturalism has to allow for meaningful differences to co-exist. We can embrace shared goals without demanding ideological purity. I think this is foundational to any pluralistic ethos really.
I think the onus is on the Christian. As a cis white male in a feminist/lgbt/etc I expect and accept attacks and criticism. It's coming from an earnest place and from experience. People have been hurt.
So when I get told, " I don't trust cis white men," I tell them I don't blame them and that I'm sorry for there pain and suffering.
I Think Christians as a dominant power structure owe that to the movements they belong.
When you say "onus" it sounds like you are arguing about something like moral responsibility. You're arguing that members of dominant social categories/groups have a moral obligation to be less sensitive to criticism than members of traditionally disadvantaged groups, as a kind of reparations for past injustices. I think that's sort of reasonable as a heuristic, but I think there's probably some limit to the usefulness of this way of thinking.
So, for example, I think "white fragility" (or "male fragility" by extension) is a real phenomenon, i.e the tendency of men, or white people in the US to interpret discussions about racism or sexism as personal attacks, or to be oversensitive to those discussions. I agree that it would be helpful if people were more open to discussions on these issues. But, I think in some large part the defensiveness is a function of the way people have been taught to think about the issues. They tend to think about them as involving individual attitudes and prejudices more so than as systemic/institutional/cultural problems. In short they think their identity is being attacked, i.e that they are being attacked for being white, or male, or Christian.
The problem is that while I agree this is
their (white, male, cis, Christian...) problem (especially from the perspective of a member of some oppressed group), from a social movements perspective I don't think it's particularly useful to sit around waiting for them to fix it themselves. If feminists want to raise consciousness, we have to work with people where they are. It feels nice to have a theory of the moral obligations of dominant groups, but I'm not sure it's that practically useful. I think it's worth our time to try to find ways to communicate effectively even accepting the failings of the people we're trying to reach. Not because it's "fair" but because it's practical.
Also, I generalized "Christian" to "dominant groups" just because I think it should be relative to a given society. Christians don't bear the kind of "onus" you are referring to in Saudi Arabia, for example. Obviously one of the more contentions areas around "intersectionality" and religion these days has to do with how to think about Muslims as both an oppressed group (in the west) but also an oppressive group (towards women, especially in the Middle East). I think the answer is that it's not helpful to overgeneralize ones stance towards these issues. One can recognize the reality and danger of Islamaphobia while also meaningfully criticizing Islam as its practiced in many countries, while also being careful about over-generalizing to a billion people. Here again I think we just run into the limits of the conceptual framework of oppression. If intersectionality gets us to recognize that there can be multiple overlapping oppressions it also means that groups can occupy both roles with respect to different other groups, and the logic of group membership is messy.