What should I say?

since coming to taiwan, i've encountered a few situations where i've had the opportunity to spread the word of Christ and share with somone on what Christianity is all about. most of those times i only had a few minutes to share the bone-bare essentials of our faith. can anyone give me any ideas on where i should start? i know what we believe but where do i start if i only have a few minutes to share with someone one message about Christianity to someone who has no concept of God, Christ, etc. ?