Mark 9:30-37 — 30 They went on from there and passed through Galilee. And he did not want anyone to know, 31 for he was teaching his disciples, saying to them, “The Son of Man is going to be delivered into the hands of men, and they will kill him. And when he is killed, after three days he will rise.” 32 But they did not understand the saying, and were afraid to ask him.
33 And they came to Capernaum. And when he was in the house he asked them, “What were you discussing on the way?” 34 But they kept silent, for on the way they had argued with one another about who was the greatest. 35 And he sat down and called the twelve. And he said to them, “If anyone would be first, he must be last of all and servant of all.” 36 And he took a child and put him in the midst of them, and taking him in his arms, he said to them, 37 “Whoever receives one such child in my name receives me, and whoever receives me, receives not me but him who sent me.”
The Son of God didn’t just come to earth and give a bunch of directives on how everyone is supposed to live; he did do that, but he does not call anyone to anything that he did not do himself. This means that Christians don’t merely follow a bunch of rules; Christians follow a person, namely God, the Son. And what’s so spectacular about this exemplary life is that he’s the only person to ever walk the earth who didn’t need to serve anyone. In fact, he’s the only one actually worthy of being served by everyone. Yet he chose to take the role of a servant because he was submitting to the Father’s will and accomplishing God’s eternal plan of redemption, which entails the ultimate benefit to others at the ultimate cost to himself. That is the mindset of being last of all and servant of all in Mark 9:35-37.