Hello, Johnny! Welcome to TOL. My material on the Old Testament is kind of long, so I'll save the New Testament material for a follow-up post.
The Old Testament
If you believe that Jesus is God the Son, then you should have no trouble believing that the Old Testament (which is made up of three sections: the Law, the Prophets, and the Writings) is God's authoritative word, because Jesus affirmed it:
Then He said to them, "These are the words which I spoke to you while I
was still with you, that all things must be fulfilled which were written in
the Law of Moses and the Prophets and the Psalms* concerning Me. " And He
opened their understanding, that they might comprehend the Scriptures. Luke
24:44-45
*Here Christ used "the Psalms" to refer to "the Writings." It's a Hebrew figure of speech in with the beginning of something is used to refer to the whole. Likewise, sometimes "the Law" is used to refer to five books of Moses, but sometimes it is used to refer to the enter Old Testament, since it is the first section. It's similar to when we might refer to an author's "bestselling title" when we're actually talking about his "bestselling book."
And as if that weren't enough...
I've emboldened places where Christ refers to Old Testament Scripture authoritatively, and I've italicized where He has quoted a specific passage.
And He answered and said to them, "Have you not read that He who made them at the beginning 'made them male and female,' and said, 'For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh'?" Matthew 19:4-5 (also Mark 10:6-8)
So God created man in His own image; in the image of God He created him; male and female He created them. Genesis 1:27
Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one flesh. Genesis 2:24
"And as it was in the days of Noah, so it will be also in the days of the Son of Man: They ate, they drank, they married wives, they were given in marriage, until the day that Noah entered the ark, and the flood came and destroyed them all. " Luke 17:26-27
Jesus said to them, "Most assuredly, I say to you, before Abraham was, I AM." - John 8:58
Then Moses said to God, "Indeed, when I come to the children of Israel and say to them, "The God of your fathers has sent me to you,' and they say to me, "What is His name?' what shall I say to them?"
And God said to Moses, "I AM WHO I AM." And He said, "Thus you shall say to the children of Israel, 'I AM has sent me to you.'" Exodus 3:13-14
[See Genesis for the story of Abraham. Note also that Exodus cites the six-day account of creation (Exodus 20:11), and that Jesus credits Moses as the author of Genesis, since it is one of the books of "the Law of Moses." (Luke
24:44)]
Jesus answered and said to them, "You are mistaken, not knowing the Scriptures nor the power of God. For in the resurrection they neither marry nor are given in marriage, but are like angels of God in heaven. But concerning the resurrection of the dead, have you not read what was spoken to you by God, saying, 'I am the God of Abraham, the God of Isaac, and the God of Jacob'? God is not the God of the dead, but of the living." Matthew 22:29-32 (also Mark 12:24-26)
"But even Moses showed in the burning bush passage that the dead are raised, when he called the Lord 'the God of Abraham, the God of Isaac, and the God of Jacob.'" Luke 20:37
Now Moses was tending the flock of Jethro his father-in-law, the priest of Midian. And he led the flock to the back of the desert, and came to Horeb, the mountain of God. And the Angel of the LORD appeared to him in a flame of fire from the midst of a bush. So he looked, and behold, the bush was burning with fire, but the bush was not consumed. Then Moses said, "I will now turn aside and see this great sight, why the bush does not burn."
So when the LORD saw that he turned aside to look, God called to him from the midst of the bush and said, "Moses, Moses!"
And he said, "Here I am."
Then He said, "Do not draw near this place. Take your sandals off your feet, for the place where you stand is holy ground." Moreover He said, "I am the God of your father—the God of Abraham, the God of Isaac, and the God of Jacob" And Moses hid his face, for he was afraid to look upon God… Moreover God said to Moses, "Thus you shall say to the children of Israel: 'The LORD God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you. This is My name forever, and this is My memorial to all generations.'" Exodus 3:1-6, 15
But when the Pharisees heard that He had silenced the Sadducees, they gathered together. Then one of them, a lawyer, asked Him a question, testing Him, and saying, "Teacher, which is the great commandment in the law?"
Jesus said to him, "'You shall love the LORD your God with all your heart, with all your soul, and with all your mind.' This is the first and great commandment. And the second is like it: 'You shall love your neighbor as yourself.' On these two commandments hang all the Law and the Prophets." Matthew 22:34-40 (also Mark 12:28-34; Luke 10:25-28)
"You shall love the LORD your God with all your heart, with all your soul, and with all your strength." Deuteronomy 6:5
"You shall not hate your brother in your heart. You shall surely rebuke your neighbor, and not bear sin because of him. You shall not take vengeance, nor bear any grudge against the children of your people, but you shall love your neighbor as yourself: I am the LORD." Leviticus 19:17-18
Now behold, one came and said to Him, "Good Teacher, what good thing shall I do that I may have eternal life?"
So He said to him, "Why do you call Me good? No one is good but One, that is, God. But if you want to enter into life, keep the commandments."
He said to Him, "Which ones?"
Jesus said, "'You shall not murder,' 'You shall not commit adultery,' 'You shall not steal,' 'You shall not bear false witness,' 'Honor your father and your mother,' and, 'You shall love your neighbor as yourself.'" Matthew 19:16-19
"Honor your father and your mother, that your days may be long upon the land which the LORD your God is giving you.
"You shall not murder.
"You shall not commit adultery.
"You shall not steal.
"You shall not bear false witness against your neighbor." Exodus 20:12-16 (also Deuteronomy 5:16-20)
[Leviticus 19:17-18 referenced again]
Then the scribes and Pharisees who were from Jerusalem came to Jesus, saying, "Why do Your disciples transgress the tradition of the elders? For they do not wash their hands when they eat bread."
He answered and said to them, "Why do you also transgress the commandment of God because of your tradition? For God commanded, saying, 'Honor your father and your mother'; and, 'He who curses father or mother, let him be put to death.' But you say, 'Whoever says to his father or mother, "Whatever profit you might have received from me is a gift to God"-- then he need not honor his father or mother.' Thus you have made the commandment of God of no effect by your tradition. Hypocrites! Well did Isaiah prophesy about you, saying:
'These people draw near to Me with their mouth,
And honor Me with their lips,
But their heart is far from Me.
And in vain they worship Me,
Teaching as doctrines the commandments of men.'"
When He had called the multitude to Himself, He said to them, "Hear and understand: Not what goes into the mouth defiles a man; but what comes out of the mouth, this defiles a man." Matthew 15:1-11 (also Mark 7:5-16)
[Exodus 20:12; Deuteronomy 5:16 referenced again]
"And he who curses his father or his mother shall surely be put to death." Exodus 21:17 (see Deuteronomy 21:18-21 for more detail and clarification.)
Therefore the Lord said:
"Inasmuch as these people draw near with their mouths
And honor Me with their lips,
But have removed their hearts far from Me,
And their fear toward Me is taught by the commandment of men," Isaiah 29:13
But He said to them, "Have you never read what David did when he was in need and hungry, he and those with him: how he went into the house of God in the days of Abiathar the high priest, and ate the showbread, which is not lawful to eat except for the priests, and also gave some to those who were with him?"
And He said to them, "The Sabbath was made for man, and not man for the Sabbath. Therefore the Son of Man is also Lord of the Sabbath." - Mark 2:25-28
And the priest answered David and said, "There is no common bread on hand; but there is holy bread, if the young men have at least kept themselves from women."
Then David answered the priest, and said to him, "Truly, women have been kept from us about three days since I came out. And the vessels of the young men are holy, and the bread is in effect common, even though it was consecrated in the vessel this day."
So the priest gave him holy bread; for there was no bread there but the showbread which had been taken from before the LORD, in order to put hot bread in its place on the day when it was taken away. 1 Samuel 21:4-6
Then Jesus returned in the power of the Spirit to Galilee, and news of Him went out through all the surrounding region. And He taught in their synagogues, being glorified by all.
So He came to Nazareth, where He had been brought up. And as His custom was, He went into the synagogue on the Sabbath day, and stood up to read. And He was handed the book of the prophet Isaiah. And when He had opened the book, He found the place where it was written:
'The Spirit of the LORD is upon Me,
Because He has anointed Me
To preach the gospel to the poor;
He has sent Me to heal the brokenhearted,
To proclaim liberty to the captives
And recovery of sight to the blind,
To set at liberty those who are oppressed;
To proclaim the acceptable year of the LORD.'"
Then He closed the book, and gave it back to the attendant and sat down. And the eyes of all who were in the synagogue were fixed on Him. And He began to say to them, "Today this Scripture is fulfilled in your hearing." So all bore witness to Him, and marveled at the gracious words which proceeded out of His mouth. And they said, "Is this not Joseph's son?" Luke 4:14-22
"The Spirit of the Lord GOD is upon Me,
Because the LORD has anointed Me
To preach good tidings to the poor;
He has sent Me to heal the brokenhearted,
To proclaim liberty to the captives,
And the opening of the prison to those who are bound;
To proclaim the acceptable year of the LORD,
And the day of vengeance of our God;
To comfort all who mourn," Isaiah 61:1-2a
And He said to them, "When I sent you without money bag, knapsack, and sandals, did you lack anything?"
So they said, "Nothing."
Then He said to them, "But now, he who has a money bag, let him take it, and likewise a knapsack; and he who has no sword, let him sell his garment and buy one. For I say to you that this which is written must still be accomplished in Me: 'And He was numbered with the transgressors.' For the things concerning Me have an end." Luke 22:35-56
"Or do you think that I cannot now pray to My Father, and He will provide Me with more than twelve legions of angels? How then could the Scriptures be fulfilled, that it must happen thus?"
In that hour Jesus said to the multitudes, "Have you come out, as against a robber, with swords and clubs to take Me? I sat daily with you, teaching in the temple, and you did not seize Me. But all this was done that the Scriptures of the prophets might be fulfilled."
Then all the disciples forsook Him and fled. Matthew 26:53-56
Therefore I will divide Him a portion with the great,
And He shall divide the spoil with the strong,
Because He poured out His soul unto death,
And He was numbered with the transgressors,
And He bore the sin of many,
And made intercession for the transgressors Isaiah 53:12
Jesus said to them, "Have you never read in the Scriptures:
'The stone which the builders rejected
Has become the chief cornerstone.
This was the LORD's doing,
And it is marvelous in our eyes'?" Matthew 21:42 (see also Mark 12:10)
The stone which the builders rejected
Has become the chief cornerstone.
This was the LORD's doing;
It is marvelous in our eyes. - Psalm 118:22-23
"I do not speak concerning all of you. I know whom I have chosen; but that the Scripture may be fulfilled, 'He who eats bread with Me has lifted up his heel against Me.'" John 13:18
Even my own familiar friend in whom I trusted,
Who ate my bread,
Has lifted up his heel against me. Psalm 41:9
Then the blind and the lame came to Him in the temple, and He healed them. But when the chief priests and scribes saw the wonderful things that He did, and the children crying out in the temple and saying, "Hosanna to the Son of David!" they were indignant and said to Him, "Do You hear what these are saying?"
And Jesus said to them, "Yes. Have you never read,
'Out of the mouth of babes and nursing infants
You have perfected praise'?" Matthew 21:14-16
Out of the mouth of babes and nursing infants
You have ordained strength,
Because of Your enemies,
That You may silence the enemy and the avenger. Psalm 8:2
