Chances are, you know who your father is or was. But how would you prove it to someone else? What if, when you were small, you had an older brother who whispered in your ear, “You know, Mom and Dad aren’t really your parents. You’re adopted”? What could you say?

These days, paternity can be established through DNA testing. A swab is used to gather tissue samples from inside the cheeks of the mother, child, and father in question, and the samples are analyzed for matching DNA markers. When done professionally, the test is highly accurate.

But DNA testing has only been around since the 1980s, and most of the time, a child’s paternity isn’t questioned. Often, in fact, we see the resemblances: the body type, the hairline, the shape of the nose. “You look just like your father,” someone might say. Indeed, when I look in the mirror today, I still see traces of my father in the silver hair at my temples and in my eyebrows.

In Jesus’ day, of course, no one had ever heard of DNA. But the identity of one’s father mattered. Jesus himself repeatedly referred to God as his Father, especially in the gospel of John. And people didn’t respond with, “That’s sweet.” Sometimes, it turned into a fierce argument.

Take the story in John 8, in which Jesus stood in the temple courts and claimed to be the light of the world. The Pharisees tried to dismiss his claim on a technicality: by law, he could not testify on his own behalf. But Jesus responded that his Father was his witness. The Pharisees misunderstood, thinking he was talking about his earthly father, and things deteriorated from there.

Even those who believed him became defensive when Jesus said, “If you hold to my teaching, you are really my disciples. Then you will know the truth, and the truth will set you free” (John 8:31-32, NIV). They objected that they were children of Abraham and had never been slaves. Jesus shot back that yes, technically, they were Abraham’s descendants (they had his DNA) but not his children, because they were wanting to kill him, which Abraham would never have done.

Tellingly, no one responded to Jesus’ accusation that they were trying to kill him. Instead, they took offense at the claim that they weren’t really Abraham’s children and doubled down. They insisted that Abraham was their father, and shortly thereafter added, “The only Father we have is God himself” (vs. 41). No, Jesus replies, you don’t belong to God. You belong to your father the devil, who is both a murderer and a liar.

That certainly stirred things up. Back and forth the argument went, until Jesus said, “Before Abraham was, I am” — which his listeners rightly heard as a claim to divinity. They picked up stones to execute him for blasphemy on the spot, but Jesus slipped away.

An isolated incident? Hardly. John 10 tells of Jesus’ return to the Jerusalem temple, this time for the festival known as Hanukkah. Some of the Jews surrounded him and demanded to know if he was the Messiah. Was it an honest question? Did they really want to know? Perhaps. But Jesus responded that he had already told them — they just didn’t want to listen. Having claimed earlier to be the Good Shepherd, Jesus essentially told them, You don’t believe and you don’t listen because you’re not my sheep.

Again, he claimed God as his Father, saying that the works he had already done in his Father’s name should be testimony enough to the truth. And then, he dropped another rhetorical bombshell: “I and the Father are one” (vs. 30). Again they tried to stone him for blasphemy. Jesus replied:

Why then do you accuse me of blasphemy because I said, “I am God’s Son”? Do not believe me unless I do the works of my Father. But if I do them, even though you do not believe me, believe the works, that you may know and understand that the Father is in me, and I in the Father. (vss. 36-38)

They tried to seize him, but he slipped away once more.

AS WE CONTINUE to study the Sermon on the Mount during this Lenten season, as we ponder what it means to pray to our Heavenly Father, we should remember that Jesus’ claims to be God’s Son were controversial. He always obeyed his Father out of love, but he wasn’t always loved by others for it. When we call God our Father, we seek to live in a way that shines his light and shows his character. There’s no greater compliment than to have someone say, “You look just like your Father.”

But it’s not always the way to make friends. To the extent that we can remember that we are following in the footsteps of Jesus, we’ll be that much more ready for Easter.