... in 300 words or less.
Blogging is something that lends itself to quick thoughts and shallow positions. Saying something substantial in three or four paragraphs is well-nigh impossible.
Something similar happens in our interactions with people. If we are Christian, and we want to convey the message of the Gospel, it can be really tough to do in the course of casual social intercourse. Perhaps it is also well-nigh impossible.
Hence the importance of social apostolate. People see what you do all the time. For the people around you on a day-to-day basis, this "conversation" is much more sustained than the vocal one. By acting like a Christian, you can preach for hours and hours. If you try to blurt out a message in a few minutes you will probably leave out the depth of the message, and possibly hurt the long-term hopes of bringing someone to the faith.
There are times to speak the Truth boldly and plainly. But these bold statements are not the stuff of the day-to-day. People can smell bullshit, and they will want to know what you are doing to back up what you say. This can be a tricky scenario. If you want to be a John the Baptist, that's great. But make sure you are living the asceticism and spiritual depth of the Baptist, as well. Otherwise you might just be an asshole.
And Jesus was definitely not an asshole.