Marketing one's Religion /Faith

One thing i never understood is this .Why do people do advertising for their faith/religion . I don't get it at all . i just cannot stand when one starts preaching about their god/ beliefs etc all of a sudden. I feel faith / practicing a religion is one's own personal choice .Like how we have certain personal stuff, this should also be a personal thing -which is too precious to be actually spoken so much about .I know and completely understand that when someone is in need of help ,we need to show them the way -share what worked for us etc .But why without asking for it? I have met people who just focus so much on their god topic.Sometimes - i wonder why do they do that ? to convert me or to make me buy their belief system ...sometimes it looks so.I believe practicing a philosophy and living by the principles is far more important than just talking about it or preaching to others about it . We can definitely share with friends if it is a great thing that needs to be told to some ..but why everyone ? and why with the intention of having someone take up that particular faith ? And most of the time the targets are people stricken with poverty ..they are lured blindly into getting converted to a particular religion by offering free food ,education for their family .. if our faith was so good , why cant all this be given without them having to convert !! why not ?? is it not ..if the intention of any particular religion or faith was to really bring happiness to people - it would do so without having too many conditions like conversions and rules as end of the day what matters is one's belief and what values he/she lives by but not whether he is wearing a cross/vibhudi or doing his namaz!