Yes, you can carry a gun at a church, temple, mosque, or synagogue in Nevada. There is no law restricting carry at a house of worship.
This includes LDS churches following the "request" of church leadership that members not carry. This edict only has the force of law in Utah.
In Nevada, if a church elder (someone with the authority to tell you what you can and can't do) tells you to disarm or leave, failure to do so would be trespassing. It's the same principle as at a store or a casino.
If the church has licensed child care facility or a school on the premises, only that part of the building would be off-limits to carry. Our understanding is that this would not apply to Sunday school.
There is nothing special about places of worship that keep them safe. For Christians in particular, Jesus promised persecution and strife for following him, and also advocated selling clothing to buy a sword if one wasn't armed. Danger and evil can strike at any place at any time, and with houses of worship being targeted, it is irresponsible not to carry there.