"I know that His command leads to eternal life...." (John 12:50)

"I know that His command leads to eternal life. So whatever I say is just what the Father has told me to say." (John 12:50)

What does "His command" mean?

Jesus is speaking of serving the Supreme Being, as Jesus indicates in the prior verse:
"For I did not speak of my own accord, but the Father who sent me commanded me what to say and how to say it." (John 12:49)
The word "command" from both verses is being translated* from the Greek word ἐντολή (entolē), which means "an order, command, charge, precept, injunction" according to the lexicon. This means that Jesus is clearly saying he is following God's orders. He is saying what God is commanding him to say. This means Jesus is saying he is serving God. He is receiving God's instructions. To follow someone else's instructions or commands means to serve that person.

He also connects "His command" to "eternal life" by saying that one leads to the other. What does this mean?

It means that serving God results in "eternal life." "Eternal life" means that we return to our natural condition as God's loving caregivers. The spiritual realm - where God personally dwells - is "eternal" because our spiritual bodies do not die as these temporary physical bodies do.

The spiritual realm is our home. 

We are each spiritual individuals who have fallen away from the spiritual realm and taken on these physical bodies.

The reason we fell away from the spiritual realm is that we became selfish, and we became envious of God. And because selfishness and enviousness are not conducive to the environment and culture of the spiritual realm, we fell away and took on physical bodies in the physical world.

Here in the physical world, we get to exercise our self-centeredness and enviousness. This physical world provides us with a dimension that lets us play out our desires to lord it over others. Here we get to pretend that we are the center of the universe. Here we get to pretend that everything and everyone is centered around me.

So we spend our physical lives trying to position ourselves as the center. We thus seek recognition, admiration and the attention of others. We seek positions of power and authority so that others will serve us and do what we say. We seek to become managers, CEOs, professors, gurus, political leaders, movie stars and business tycoons, all in an attempt to have authority and power.

Ultimately, we are seeking God's authority. 

If God's position was up for election we'd all be running for that position. But that position is not available. So we'll take the highest position we can take. And for those cannot get positions with authority and power over large groups - whether it be companies, governments, populations, fans or followers - we will settle for having authority over our families, community clubs, or so-called friends.

Thus we each pretend to be experts and leaders, showing off our great wisdom with speeches, blogs and news television shows.

Jesus, on the other hand, does no such thing. He does not take the position of being authoritative and wise. Instead, he says:
"So whatever I say is just what the Father has told me to say."
Jesus could have easily taken the credit for all his wise parables and his miraculous healings. He could have even called himself the Supreme Being - as many self-appointed gurus are now doing. But he didn't. He humbly clarified to his students that he was just following orders from God. He was God's humble servant - saying and doing what the Supreme Being wanted him to.

With his statement and his actions, Jesus is clarifying our path to leave this world of hatred, violence, bloodshed, greed and jockeying for position. Jesus is simply telling us that by becoming one of God's humble servants like he is, we will return to our natural position in the spiritual realm.

Why does becoming a humble servant of God allow us to return to the spiritual realm?

Because the spiritual realm is a place of love and devotion. The citizens of the spiritual realm are in love with Supreme Being. He is the most beautiful, the most compassionate, the most reliable and the most loving person. So they have dedicated their lives to Him. Thus they each exchange a personal relationship with the Supreme Being. Their relationship is so intimate that they do not even realize the He is God. They are simply wrapped up in their attachment to Him.

When a person loves another person, they naturally do what pleases them. This is called loving service. This is distinguished between forced service. We can see that God never forces us to serve Him - which is why those of us who don't want to serve Him are not serving Him.

Beneath our attempts to gain power and authority, the spiritual realm is that place we are all seeking. We all seek a place where everyone lives in peace and harmony, and everyone loves each other. We all seek a place where we are cared for and appreciated. We all seek a place where we are protected.

This is the spiritual realm.

And we all seek that special person who will care for us and protect us. We all seek that person we can trust without a doubt. Someone who will never abandon us. Someone who will fulfill our needs. Someone we can turn to anytime who will listen to us and always be there for us.

This is the Supreme Being.

Jesus was in love with the Supreme Being. This is why Jesus walked the countryside for years with no home, no job, no source of income. This is why Jesus suffered on behalf of his teachings. This is why Jesus beseeched anyone he spoke to give their lives to the Supreme Being and serve God. Jesus was doing what pleased his Beloved. He knew that God wants us all to come back to Him, because God loves us unconditionally. So Jesus, being in love with the Supreme Being, wants to please Him. This is why Jesus emphasized one particular teaching, just as Moses before him had:
“‘Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment." (Matt. 22:37-38)

*Here is the translation of Jesus' statement according to the Gospels of Jesus:

“I know His instructions are eternal life; therefore the things I say, I say just as the LORD has taught me.” (John 12:50)