Once a believer, always a believer? Possible Duplicate:
  Once saved always saved. Is eternal security Biblical?  




Recently, I had a conversation with a (new) friend that started off with him telling me how he had been a devout Christian, perhaps even a believer (to use some Christianese), but had lost his faith due to later events. This struck me as a bit odd, because I had always thought that once you had put your faith in Christ, then you could never lose it. I went hunting for the verse that I was thinking of (and that he confirmed as existing), but couldn't find it. So...was I right? Is it true that once you put your faith in God and Jesus, then you can never lose it, especially under persecution?

To clarify, I'm more interested in whether someone else can cause you to lose your faith as opposed to you turning away from God. The "Once saved always saved." question deals with people turning away from God, but does not deal with other people "causing" a deconversion.

Biblically-based answers are prefered.
There are numerous stories of strongly religious Christians converting to atheism or various non-Christian religions.

There are also a whole slew of Bible quotes about losing faith listed here.  Here's one in particular from 1 Thessalonians 3:5-6 (ESV):


  5For this reason, when I could bear it no longer, I sent to learn about your faith, for fear that somehow the tempter had tempted you and our labor would be in vain. 6But now that Timothy has come to us from you, and has brought us the good news of your faith and love and reported that you always remember us kindly and long to see us, as we long to see you—


I'd say it's very possible to lose faith.



Edit: though people are not mostly given credit for making others fall from faith, there are a few passages in the link above.  For example, 2 Timothy 2:16-18 (ESV):


  16But avoid irreverent babble, for it will lead people into more and more ungodliness, 17and their talk will spread like gangrene. Among them are Hymenaeus and Philetus, 18who have swerved from the truth, saying that the resurrection has already happened. They are upsetting the faith of some.