You can never unlock 'immortality' per se, for technical reasons.
Nevertheless, when aging will be conquered, the market value for religion on the grounds that it promises you eternal youth will be greatly diminished. People may think they're deeply devout or whatever, but I suspect most religious persons are just like agnostics in most respects and believe in God for mostly superficial, existential angst reducing reasons.
Not necessarily. Many of devout faith will simply call modern medicine/science an
abomination when we get to the point of Deus Ex augmentation. Stem-cell research already sees lots of pressure to be held back because it's the upset that man is going "too far" to meddle with
Gods nature. Ethics are hugely important in the realm of science/medicine/psychology, but many of faith aren't arguing from nuanced places on ethics, it's simply if it seems to be blasphemy, it's unethical.
As much as many use God/religion to fill their fears of death, they'll resist against "immortality" because ultimately they want to meet their maker/meet their dead loved ones again (two of the biggest promises and selling points of religion). The existential angst of a human considering life/death manifests its ways in countless examples. Even the agnostic/atheist may scoff at the concept of immortality, as death is often seen to give life
meaning. Although, by "immortality" I presume most of us, for now, are just arguing on the grounds of extending life expectancy dramatically, not actual outright immortality. The next logical steps such as introducing artifical organs, either grown to appear natural or outright machine-made components. "Super-drugs" that can cure nearly everything. Or ways to reverse the ageing process, in part largely caused by oxygen. Things like that, which could eventually add tens of years onto human life.
Maybe waaaaaay down the line if we haven't destroyed the planet, there will be some sort of concept of capturing the brain and transplanting consciousness. Who knows, that's into realms we'll never get to witness as we'll all be long dead. A lot of belief in religion is on a downward trajectory in some areas of the world where young minds are given a wealth of information to research and choose from. It'll never outright go away though, it's part of humanity that many when faced with existential angst around being/death/meanings, they'll fill that void with everything their eyes see having to have been created by a God/higher power. Ultimately, it will most likely end up humans that get to
play god, and as I said that will upset many of faith. I really wish I could be around to see truly advanced AI. It's both a terrifying concept and a magnificent one.
A lot of books/films and debate already touch on ethics around AI, when AI itself may reach a point of "lifelike" response/question/meaning. Many say that will only manifest if humans ever give AI that kind of power, but who knows. Again, things that are way outside our life expectancies, if they ever come about. Of course, people from religious backgrounds will forever argue without a "soul" something isn't
alive. Cue the vicious debates about whether AI could ever be considered alive, if it's capable of human-like (or even more advanced) intelligence/awareness.