This passage is found in the RCL , Year C, most recently in the summer of 2016. In this case, it is Genesis 18:1-10a
This passage is found in the Narrative Lectionary Year 2 (Most recently: Sept 20, 2015).
Summary: Right after the beautiful image of Adam and Eve in the garden, we get a glimpse of real families and the problems: infertility, if not infidelity and all sorts of sibling rivalries. What is at stake? Can God be a faithful God over and against human sin and weakness? The answer here is clearly "yes."
איש ("ish", meaning "man", 18:2) The word here does not mean angels, dieties or anything else divine. It simply means man. Which raises all sorts of interesting questions. First, do the three men represent the Trinity? This seems unlikely. Why? First, the two men separate themselves from the "LORD" (18:22). This seems a strange behavior for the Trinity, supposedly united in an eternal dance of love. Second, the two men are referred to as "messengers" (or angels in 19:1). Even the New Testament refers to them as angels (Hebrews 13:2). It seems strange to refer to the second and third person of the trinity as messengers/angels!
Side note on ancient languages: In both Hebrew and Greek, the word for messenger (αγγελος or
מלאכים) is the same as the word for angel (think ev-angelical means good -message!).
Second, can God take a human form without the incarnation? This seems really intriguing. Was God merely appearing as a human...or was God actually taking human form...or is God always in human form? Well, for starters, food was consumed (18:8). Real food! Real stomachs! This was not just a ghost, but a living human being. It seems possible that God could, in fact, take a human form...but this makes a strange case for the significant of Christmas. The significance of Christmas is not that God became human but HOW God became human, namely as a virtual refugee born among animals and proclaimed to shepherds.
צחק ("saqaq", meaning "laugh", 18:12) Simply play on words: Sarah "laughs" (saqaq) and will name her child "he laughs" (Yitzhak, or anglicized, "Isaac")
היפלא ("hi-iphaleh" two words, meaning "if wonderful", 18:14) Some translations take this in a negative way, "Is anything too difficult or too hard." The root here is one of wonderful and miracle -- is anything too amazing, too miraculous for God.
TWOT offers a great insight into this word (really root word) about the fact that the miracle is not as important as the revealed fact that God is for (or against) us.
"Preponderantly both the verb and substantive refer to the acts of God, designating either cosmic wonders or historical achievements on behalf of Israel. that is, in the Bible the root pl° refers to things that are unusual, beyond human capabilities. As such, it awakens astonishment (pl°) in man. Thus, the "real importance of the miraculous for faith (is) -not in its material factuality, but in its evidential character... it is not, generally speaking, the especially abnormal character of the event which makes it a miracle; what strikes men forcibly is a clear impression of God's care or retribution within it" (Eichrodt). We may add that it is essential that the miracle is so abnormal as to be unexplainable except as showing God's care or retribution."