If the pill is only claimed to increase life expectancy and has been shown to do so then it is not religious. If it has not been shown to do so then it is in effect religious in nature (or snake oil, depending on who believes what and what the pill actually does).
I fully expect life expectancies to rise and the quality of life as we age to also increase. I think that this is in agreement with science as we currently understand it. However, this is not what is claimed on this site. Terms like millions of years or more are given with great fervor even though there isn't any evidence of that being possible.
I wasn't giving a literal example. My point was that "transhumanists believe X, some religions believe Y, which is similar to X, therefore transhumanism is a religion" is a stupid argument. After all, Abrahamic religions and transhumanists agree that snow is white, but nobody would consider that a good argument.
If you wish to criticise the beliefs held by transhumanists you must criticise the beliefs directly, not reason by analogy to superficially similar beliefs held by other groups.