What was with that Hair? What made it give him Strength? First I had to come to understand the term Nazarite - and the distinct vow that they take.

“When either man or woman shall separate themselves to vow a vow of a Nazarite, to separate themselves unto the LORD: He shall separate himself from wine and strong drink … no razor shall come upon his head … he shall be holy” (Numbers 6:2,3,5).

First, Nazarites refrained from alcohol. Second, they had to avoide being near or touching dead things - including family gravesites. Third, during the vow, they could not cut their hair.

There are three Nazarite examples from the Bible: Samson, Samuel, and John the Baptizer. This uncut hair made them distinct as followers of and dedicated to God.

SAMUEL - when his mother Hannah dedicates him, God says that no blade shall come to his head.

1 SAMUEL 1:1  And she made a vow, saying: "Lord Almighty, if you will only look on Your servant's misery and remember me, and not forget Your servant but give her a son, then I will give him to the Lord for all the days of his life, and no razor will ever be used on his head." For he will be great in the sight of the Lord, and shall drink neither wine nor strong drink. He will also be filled with the Holy Spirit, even from his mother's womb."

JOHN the BAPTIZER -  The angel Gabriel spoke to Zacharias his father and said:

Luke 1:15   For he will be great in the sight of the Lord, and shall drink neither wine nor strong drink. He will also be filled with the Holy Spirit, even from his mother's womb."

So let's talk about Samson - And let's talk about this hair. Why was Samson's hair his Strength? Was it because of the promise and devotion to God, demonstrated through this Nazarite Vow? I think so. Samson did not make the vow - his parents did in order to have their son. His mother said to the Angel of the Lord:

Judges 13:3-7  The angel of the Lord appeared to her and said, "You are barren and childless, but you are going to become pregnant and give birth to a son. Now see to it that you drink no wine or other fermented drink and that you do not eat anything unclean. You will become pregnant and have a son whose head is never to be touched by a razor because this boy is to be a Nazarite, dedicated to God from the womb. He will take the lead of delivering Israel from the hands of the Philistines.

What about Jesus? A "Nazarene" is not the same as a "Nazarite":

Jesus was raised in Nazareth (and hence called a Nazarene - Matthew 2:23) but he was NOT a Nazarite. He practiced things that would not be permitted if he were under the vow.  For example, Jesus could not be a Nazarite because He drank wine. (Matthew 11:19, Luke 7:34) Additionally, He also came close to or touched the dead bodies of at least three people (Luke 7:11 - 15, 8:49 - 55, John 11), which would have been forbidden for Him to do.

The New Testament states that men were expected to have short hair (1Corinthians 11:14, 16). Since Christ never took up the Nazarite vow for Himself, which would have allowed Him to wear long hair, He probably always wore His short. Interesting - right?  

Back to Samson and that hair: The summary from Bible Study tools:

Samson was God’s chosen man during a time when the judges ruled Israel. From birth, he was destined to liberate Israel from the Philistines. While Samson was incredibly strong in body, he was very weak in character. Among his character flaws was a fondness for Philistine women. One was named Delilah. 

Samson then fell in love with a beautiful Philistine woman named Delilah. The rulers in Philistine came to Delilah and offered her money if she found out what made Samson so strong. Delilah went home and made a great meal for Samson and asked him what made him so strong. Samson responded that if he was tied up with seven new bowstrings that had not been dried, he would lose his strength.

Delilah went and told the rulers who instructed her to tie up Samson in his sleep. To Delilah's surprise, Samson had tricked her and was able to break free. Samson again told that he would lose her strength if tied up with bowstrings but that they had to be new and never used. Delilah again tried to trap Samson while he slept but he was able to break free. Delilah was very hurt by Samson and questioned his love for her since he could not share his secret to his strength.

The next day Delilah asked Samson continually about his strength and bugged him so much that he finally told her the secret to his strength - that he was given his strength at birth by God and that if his hair was cut he would lose his strength. That evening as Samson slept, Delilah cut his hair and called in the Philistines. The Philistine men were able to capture Samson. They barged in, gouged his eyes out, and took him to prison in Gaza. 

The Philistines brought Samson out before a great crowd of rulers and thousands of people gathered in the temple to celebrate his capture. Samson's hair had begun to grow back and as he leaned against the pillars of the temple, he prayed to God for strength once more to defeat the Philistines. Samson used all of his might and pushed down the temple, killing himself and thousands of Philistines and rulers. 

God forgave Samson and still accomplished great things through Samson. It was through Samson's destruction of the temple and his death that the Israelites were freed from the Philistine rule.

So Samson was strong, unusually strong, even when very young. There is a bible story where a lion jumped on him and he killed it with his bare hands.

Judges 14:5-6  Samson went down to Timnah with his father and mother. As they were entering the vineyards of Timnah, a young lion suddenly came roaring at him. 6 The Spirit of the LORD rushed upon him in power, and he tore the lion apart with his bare hands as he might have torn a young goat. But he did not tell his father or mother what he had done.

It was certainly a "sign from God" that Samson would later tear apart the Philistines as easily as he had torn apart the lion. This is a theme throughout God’s plan for his people, including us. A small event prefigures a much greater event later on.

Samson was too timid and shy to become a leader for the Israelites on his own. He thought of a more indirect way to harass and bother them - he riddled them. After killing the lion, he saw bees take over the carcass, so his riddle was this: 

"From the eater came out food, and out of the strong came out sweetness. What is it? The eater refers to a lion, the predator of all predators, and the sweetness refers to honey. Thus on the seventh day, when the Philistines came to Samson they answered him "What is sweeter than honey and what is stronger than a lion?"

The Phillistines needed a few days to figure this out - and they went to his bride and told her to get answer or they would burn down her parents home. Okay, but this is just the first time he gave in, and was betrayed by the woman he was with. He burned foxes tails to destroy crops. He killed 1,000 Phillistines with a donkey's jaw bone. He was strong, amazing and angry.

Let's jump to the famous Delilah and that hair:. Delilah was most likely not a Jew because of her hometown. Most accounts have her labelled as a "Harlot". Either way, Samson was a player, and he was smitten with her. Their sexual tension was noted, the tying up and breaking bonds at the last moment. The Phillistines bribed her to find out what gave Samson this extraordinary strength. Evenutally, he gave in to her and told her his secret. (Again!) And as he slept, she snipped his do and took his power. How did she trick him?

"If you bind me with seven moist ropes, then my strength will dissipate,” Samson told her. “If you bind me with new ropes that were never used, I will become like an ordinary man.” “If you place my hair on a weaving rod, I will become weak.” Each time, Delilah would try the methods on Samson while he slept. Each time, she would cry, "Samson, the Philistines are upon you!" and Samson would rise to his full might, completely unaffected by whatever she tried. 

Tearfully, Delilah told him - How can you say 'I love you' while your heart is not with me? These three times you have mocked me, and you have not told me wherein is your strength so great."   Finally Samson told her the secret of his super strength: "A razor has never come upon my head, for I am a Nazarite to God from my mother's womb. If I will be shaven, then my strength will leave me, and I shall become weak and be like any other man."

So he was taken, arrested and paraded around. He asked himself to be led to the pillars of the building so he could rest for a moment. There - he prayed again to God and said:

"Oh, God, give me strength this once. Let me avenge myself on these cruel Philistines that they may know that you are the only God. It matters not if I die with them!"

Suddenly, he once again felt the spirit of God in him. Samson stretched out his hands, tearing down the pillars supporting the building. The next instant, the walls and the roof came crashing down, destroying the entire building. Every single Philistine, together with Samson himself, was killed in the great crash. That day, Samson killed more Philistines than he had throughout his entire life.

above is in part, courtesy of https://www.chabad.org/

It is not, then, that Samson’s strength resided in his hair (as popular renditions of the biblical story tell) but rather in his vow — his long hair being a consequence of this lifetime consecration to God. (And By the way: Delilah  was never mentioned again. Did  Yahweh smote her?)