well... isn't that what true faith all about? if you are anything less than that then you don't have faith... you doubt your god...
when you accept christ, for example, as the son of god, thus the only savior, the only path to god and heaven, the almighty, the omnipotent, the one and only one, whose word is the absolute truth and nothing but truth, how can you allow yourself to sit down and listen what the other person has to say? that would mean that your faith in your god is not perfect... you have doubts in your mind about your god...
furthermore, when you accept christ, for example, as the son of god, thus the only savior, the only path to god and heaven, the almighty, the omnipotent, the one and only one, whose word is the absolute truth and nothing but truth, when you know you have found the path and the only path, how can you sit aside and watch your fellow friend, compatriot, or any other person for that matter live in darkness, without god, walking a wrong path... wouldn't that be selfish act to not tell him/her about the truth, about the god, about the path, illuminate him/her? wouldn't it be the most unchristian thing to do, to not share the goodness with your neighbor?
either you accept christ, for example, as the god, the perfect being, or you don't... there is no between, there are no buts or ifs... there is no half christian... anything less than perfect devotion and absolute doubtlessness makes you no christian...