What is Your Motivation?

"For the Enemy will not be used as a convenience...Only today I have found a passage in a Christian writer where he recommends his own version of Christianity on the ground that' only such a faith can outlast the death of old cultures and the birth of new civilisations'. You see the little rift? 'Believe this, not because it is true, but for some other reason.' That's the game." (p 127)

Throughout the course of reading this book I have discovered some very interesting things...but this information may be, in fact, one of the most thought-provoking ideas I have read.
The idea that we, as Christians, use God as a convenience is true...I believe. However, I think that there may be a thin line between using God as a convenience and 'conveniently' reaping the benefits that come with Christianity. Nevertheless, I do believe that Christianity is attractive to people for many reasons- not only for the one it should be- because it is true. So...how do we come to the mindset of viewing Christianity purely as truth?
I think a good example of choosing why to believe is represented in the difference between inductive and deductive reasoning. With inductive reasoning you draw a conclusion- you are believing this because it is true- and then you see the evidence of its truth. However, when people use deductive reasoning they see the evidence and then draw the conclusion that it is true.
I obviously do not have the answers to this question...but I do have other questions. For example- Is it wrong to believe Christianity is true because of the evidence, instead of relying purely on faith? If so, what does this mean for people who promote Christianity and the good it brings to people's lives?
I suppose this question can only be answered individually- by looking inside at our own motivations.