Who is Jesus?

Mark 6:3
(3)  Is not this the carpenter, the son of Mary and brother of James and Joses and Judas and Simon? And are not his sisters here with us?" And they took offense at him.

(3)  οὐχ οὗτός ἐστιν ὁ τέκτων, ὁ υἱὸς τῆς Μαρίας καὶ ἀδελφὸς Ἰακώβου καὶ Ἰωσῆτος καὶ Ἰούδα καὶ Σίμωνοσ; καὶ οὐκ εἰσὶν αἱ ἀδελφαὶ αὐτοῦ ὧδε πρὸς ἡμᾶσ; καὶ ἐσκανδαλίζοντο ἐν αὐτῷ. 

Mark 6:50

(50)  for they all saw him and were terrified. But immediately he spoke to them and said, "Take heart; it is I. Do not be afraid."

(50)  πάντες γὰρ αὐτὸν εἶδον καὶ ἐταράχθησαν. ὁ δὲ εὐθὺς ἐλάλησεν μετ' αὐτῶν, καὶ λέγει αὐτοῖς, Θαρσεῖτε, ἐγώ εἰμι· μὴ φοβεῖσθε.

I really wanted to write on both points today because I think both speak to some misconceptions about who Jesus is.  The first regards this strange idea of the perpetual virginity of Mary.  This is a dogma that has evolved over the centuries and has really become quite puzzling to me.  There are other words that could have been used to refer to "cousins," but here Mark chose to use ἀδελφὸς and αἱ ἀδελφαὶ to speak of the men and women who were in his family.  I have heard it said that these could be understood as male and female cousins, but the most natural reading of these words is as translated in the ESV.  Jesus had half-brothers and half-sisters.  Therefore, Mary and Joseph had normal relations as husband and wife.  I don't think this detracts anything from Mary, but it does attack a dogma.

The other is a translation that I don't really understand.  Quite literally, Jesus says, "Take heart; I am.  Do not be afraid."  I'm not sure where "It is I" comes from other than the KJV did it that way and English translations tend to follow suit.  I think that "I am" is a lot more powerful in addition to being the most natural rendering of ἐγώ εἰμι.  

Just off the top of my head I see how well this would preach.  Jesus was speaking words of comfort to the disciples.  Why should they take heart?  "I am."  Where have we heard that before?  Exodus 3:14.  There is another construction that Jesus could have easily used if He wanted to convey the meaning of "It is I."  Instead, He chose to use "I myself am."  Just as God told Moses to tell the Hebrews, in this case the disciples could be reassured because "I am" was with them.  

Is the great "I am" with you?  Do you take comfort from this fact?  I find that this little phrase gives me pause once again.  It is so easy for me to take my relationship with Jesus for granted because of familiarity and routine.  I never want to lose sight of the fact that I know the great "I am."