This is the classic (though slightly edited) scene from the movie City Slickers. Several eastern urbanites with issues at home go on vacation together to a dude ranch out west where they work as cowboys. The trail boss, an old crusty cowboy named Curly (Jack Palance), pulled aside one of the city slickers (Billy Crystal). "One thing!" he said. "Life is all about one thing." When Billy Crystal asked what that one thing was, Curly said that he would have to find that out for himself. The secret of life is that there is one thing... and it's our job to find out what that is. "One thing!"
That reflects several scenes from the life of Jesus. One is in Luke 10 where Lazarus' sisters Mary and Martha are entertaining Jesus. Or rather, Martha is preparing to entertain Jesus with all the details of cooking and cleaning that go along with that while Mary is sitting and listening to Jesus. Mary finally lashes out at Mary... and at Jesus Himself, "Lord, do you not care that my sister has left me to serve alone? Tell her then to help me" (Luke 10:40, ESV). Mary wasn't pulling her fair share of the housework, and it was Jesus' fault for monopolizing all of her time! Jesus replies gently, "Martha, Martha, you are anxious and troubled about many things, but one thing is necessary" (Luke 10:41, ESV). OK, Guys, when you are getting ready for company and your wife is rushing around fussing over all the details, I strongly suggest you NOT use this "Martha, Martha" line. Jesus' point here isn't that meal preparation with all of it's attendant details is unimportant. His point was that Martha, like Mary, needed to find out what was her one thing.
That scene from City Slickers is also mirrored in Mark 12:29-31. Here Jesus has been fielding a series of hot potato questions tossed to him by enemies. After sweeping aside their petty arguments, Jesus is approached by a teacher of the law who is impressed by His answers, and he has a question of his own, "Of all the commandments, which is most important?" Listen to the Lord's answer (Mark 12:29-31, ESV).
The most important is, ‘Hear, O Israel: The Lord our God, the Lord is one. 30 And you shall love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’ The second is this: ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these.
God's kingdom is a single-minded love for and pursuit of God. His oneness is the central fact of our faith, and our "one thing" must be all about God. The greatest command is love God heart, soul, mind, and strength. One of the struggles we face as Christians is that we pulled in so many different directions by so many different things. Not only are there things competing for our time and our attention; these things are also competing for our loyalty. Our world tells us that there are many things that are important. That's why Jesus told the Rich Young Ruler to give all to the poor and follow Jesus. He told him, "You still lack one thing" (Luke 18:22). The Ruler was unwilling to make God his "one thing" because his wealth and position were already occupying that position. His "one thing" wasn't God.
What is our one thing? Have we figured that out yet?