John hasn’t said anything about Mary or Martha until chapter 11. Their brother, Lazarus, has died. Jesus loved them very much (11:5). He understands the circumstances that are unraveling are for the glory of God, so that the Son of God may be glorified through it (v. 4). He is acting so that they may believe (v. 15).
I don’t know exactly why John tells us what he does about Mary and Martha. Both were mourning. Martha goes to meet Jesus when she heard he was coming, Mary just remains seated in the house (v. 20). I don’t think that the difference of response here has any moral significance. It would be easy for us to read Luke 10:38-42 into this story. We might think that Martha is anxious, Mary is chill. Martha goes in haste to nag Jesus, Mary just relaxes until he gets there. Speculation can be like walking on the moon. We need more gravity here. What does John say!?
Don’t overreact here as if there is a brutal juxtaposition between the two sisters. They actually say the exact same thing when they see Jesus–if you had been here!… (v. 21, 32). It is just that John gives us a little with Martha. And what he shows us is that she believed Jesus. In a Peter-Matthew 16-like fashion she confesses Jesus as the Christ. Jesus’ intention to procure faith by this miracle is definitely finding its fulfillment in Martha, before He has even done anything.
She acknowledges Jesus’ unlimited power (v. 22). She affirms the resurrection and is sure of her eschatological hope (v. 24). She believes Jesus is the Messiah (v. 27). That He is the Son of God (v. 27), that He is the One promised and sent and accomplishing redemption (v. 27).
And this is it. After this story we only see Martha one more time in 12:2 over dinner.
She is for the reader. I love Martha. She reminds me of my mom. Martha is a realist. Jesus is coming but she goes ahead to meet Him. He is about to call Lazarus forth and she mentions that he smells bad. Her motion is amoral. There is no “one thing necessary” scene here with background choir music and a sparkling head. But John shows us one of the most beautiful dialogues between Jesus and anybody. Martha believes in Jesus. Look at how she believes in Jesus!
John wants us to believe in Jesus the same way.