When we do not understand something it is usually because we have a wrong idea of how it works. When the first automobile drove into a village in a remote part of Africa, one man said it must have a donkey inside it. Another said with great authority that a donkey would not be able to move such a big load of passengers and luggage. It must be a mule. A third said that was ridiculous, no mule could move that fast, it must be a horse galloping. You can imagine the way the discussion never explained what was really moving that car.
Similarly Nicodemus and the Jerusalem rabbis were totally unable to grasp how Jesus related to God because they did not understand the family love relationships within the three Persons of the Trinity.
The Pharisees assumed that God wants us to obey him. So by studying the Old Testament they had deduced 615 rules that had to be obeyed. Among these there were 39 things which were prohibited on the sabbath day. Some of you can remember the gloomy Sundays when you were young, and were not allowed to do anything you enjoyed. And Orthodox Jews in Jerusalem still try to saddle people with even stricter rules about keeping the sabbath. So what the Pharisee "experts" discussed was which of the rules were the most important if you wanted to make it to heaven. And they assumed that anyone who did not try to keep the law would be sent to burn in hell.
But Nicodemus had heard that Jesus had explained how God the Father was not interested in their Pharisee rules. God is more like the most loving and wise parents we could imagine. Their aim is for the children to be happy and secure in their family, learn to love and be loved, and develop the skills they would need to play their part in the world. And for that making them feel guilty about not obeying rules would not be helpful at all. As Jesus explained later in the chapter, "God did not send the Son into the world to condemn the world, but in order that the world might be saved through him" (3:17)
Secondly Nicodemus needed to understand about God the Son. Like other Jewish people of that day, the Pharisees hoped that God would send a Messiah who would drive out the Romans, and bring in a time of peace and prosperity. What they had forgotten was that God the Son was already the reigning Messiah King spoken of in the Psalms and the Prophets. "O Lord, our Sovereign, how majestic is your name in all the earth . . . the Lord sits enthroned forever, he has established his throne for judgment. He judges the world with righteousness . . . the Lord is my Shepherd" (Psalms 8:9, 9:7, 23:1, etc).
What Nicodemus, the great Rabbi, had not grasped was how that reigning Lord of the Old Testament, who had taken birth in Bethlehem, was right there talking to him face to face. As the Gospel goes on to explain, The Father "so loved the world that he gave his only Son, so that everyone who believes in him may not perish but may have eternal life" (3:16). No wonder Nicodemus was puzzled and found it hard to understand.
Thirdly the rabbis had forgotten about the Holy Spirit. The Old Testament makes clear that the only way a leader could lead in the right way was by the Holy Spirit (Judges 3:10, 6:34). Great art could only come by inspiration (Exodus 35:30-35). The Holy Spirit was the source of all wisdom (Proverbs 2:6-10, 8:14-19, 27-31, James 1:5, 3:17). And the prophets received their messages and understood what they meant from the same Holy Spirit. But instead of looking to the Holy Spirit to understand the Word of God the rabbis poured over the commentaries of other rabbis. That is why Jesus told Nicodemus that "the wind (in Hebrew ruakh means both wind and Spirit) blows where it chooses, and you hear the sound of it, but you do not know where it comes from or where it goes. So is everyone who is born of the Spirit" (3:8). Nicodemus needed to be born again to begin his work on new foundations. The wind of the Spirit would need to blow through his lecture notes. And that was hard for a famous teacher. "How can anyone be born after growing old? Can one enter a second time into the mother's womb and be born?"
And that is our problem if we find God as a Trinity of three loving persons hard to understand. Understanding is only possible after experiencing the reality.
But imagine what happens when one of those villagers in Africa learns to drive. The idea of a donkey, or a mule, or a horse instead of an engine becomes ridiculous. Now the problem is quite different. If he fails to fill the gas tank for a journey, nothing moves. And without water to cool the engine or oil to lubricate the engine the car comes to a grinding halt
Similarly until they have experienced the Father loving them, and the Son as their Lord and friend, and the Holy Spirit's inspiration, people cannot understand that God is a Trinity of three Persons. They give every other explanation of what God is like but the right one. And if we try to live without talking to God as our loving Father, or to Jesus as the King of the Kingdom of Heaven, or to the Holy Spirit for the inspiration we need, our spiritual life comes to a grinding halt.
The experience that Nicodemus was missing comes by beginning to talk to the Father like a little child chattering to his or her parents. Also by talking to Jesus as Lord and personal friend, and by asking the Holy Spirit for wisdom. We then discover that it is as simple for us as the experience of driving a car. And once we begin, the mystery becomes easy to understand. We discover that God is love, and the three Persons of the Trinity are held together by the love that existed between them before the foundation of the world.
That is the meaning of our baptism in the name of the Father, and of
the Son and of the Holy Spirit (Matthew 28:19), and it is what we
celebrate with awe and wonder on this Trinity Sunday.