Interesting question:
I really don't like to use the word "christianity" because of the range of people who use this term. We could argue about christians that have done this and have said that.. etc etc..
So, for a person who believes that the Bible is God's perfect, timeless word, the answer is quite simple. What is best for them would be Christ. (Not christianity.. that sounds more like an antibiotic or a condition..)
I say this because someone who believes the Bible is God's word, would believe that our physical existence is miniscule in the world of everlasting existence. According to the Bible, and in a nutshell..
we are proven to be guilty of doing wrong and doing wrong is contrary to God's perfection. His standard is perfection and we can never attain that.. And the price for one sin (let alone many) is death -- not physical death, but spiritual death. Spirtiual life being the everlasting life. So if he loves us.. he needs to find a way to set us free of our wrong doing and of our spiritual death. So he sets up a way for us to choose our own destiny. Christ (god in human form) is killed by men, and then he raises himself from the dead. His death was payment for all sin of all people past and present. His coming back to life was proof that we too can be given spiritual life.
So with that information as the basic principle.. a believer in the Bible as God's word (interpretation of certain parts of the Bible is another thing alltogether.) would be that this world is only a small, painful time in eternity, where we choose what the rest of our lives will be..
either payment for our imperfection or an eternal life.
So this life is temporary and the important part is our eternal existence, and therefore the only choice that would be best for them would be to belive in Christ.
It sounds sort of callous in the sense that one is almost discrediting a person's pain in their physical existence.. but I would probably suggest, that when compared to our eternal existence.. our choice is a very important one and a "christians" choice could only be the belief in Christ.