Its hard to understand why you should think for a minute that Jesus taught anyone to follow any other god than the God of the Jewish Tanakh (ie the Old Testament). If you can add to your question to show how Jesus's teaching differs from the Tanakh then that would be helpful. As far as the Christian is concerned nothing Jesus taught contradicts the Tanakh, when the Tanakh is rightly understood: if you think it does then please tell us how.
[You have added some more to your opening statement and it is now clear what you are driving at. The resurrection by itself does indeed show that Jesus is from God, and that everything he said during his life was true, otherwise God would not have given a plain demonstration of his approval of Jesus by raising him from the dead. What the resurrection, by itself, cannot do is demonstrate that Jesus of Nazareth is that promised Messiah of the Old Testament. In order to demonstrate that, the resurrection must fulfill the prophesies of it in the Old Testament.
This is my point, the Gospel is not "just" that Jesus is the Son of God: it is that he is the promised Messiah of the Old Testament; and the resurrection, like many other events in the ministry of Jesus, is prophesied in the OT and fulfilled in the ministry of Jesus. The New Testament would be very lacking if it were alone, if there was no Old Testament from the same God.
When Paul preached to the Greeks in the midst of the Areopagus at Athens he felt no need to prove his beliefs by any reference to the Old Testament. and he finished his message saying:
The times of this ignorance God overlooked/winked at: but now he commands all men everywhere to repent: because he has set a day, in the which he will judge the world in righteousness by that man whom he has ordained. And of this he has given assurance (some versions say "proof") unto all men by raising him from the dead. (Acts 17:30,31)
The Old Testament, then, is not necessary to prove the resurrection, Paul made no use of it in his sermon. But the resurrection must not contradict the OT, as Isaiah says:
To the law and to the testimony: if they speak not according to this word it is because there is no light in them (Isaiah 8:20).
So it is not correct to claim that "In and of itself, the resurrection proves nothing. You must bring independent proof from outside the New Testament so as no to be guilty of circular logic." Paul brought no evidence from the OT. If it is circular logic to restrict to the NT alone then why isn't it circular logic to restrict to NT and OT alone? The truth is that the NT has sufficient evidence within itself to prove it is the Word of God (- just as the OT does also -) without depending on the OT for proof. But as Isaiah 8:20 shows what is needed is to show that the resurrection, and the NT and the OT all agree together, that the NT does not contradict the OT.
Of course, the resurrection is no proof to those who do not want to believe: nothing is. Jesus ended one of his parables with a man claiming:
"'But if someone goes to them from the dead then they will repent.' But he said to him 'If they will not listen to Moses and the prophets, neither will they be persuaded even if someone should rise from the dead'" (Luke 16:30,31).]
Jesus brings us to the same God, because he, his death, and his resurrection fulfill the prophesies of the Tanakh:-
The resurrection is found in many places in the Tanakh such as here:
After two days will he revive us, in the third day he will raise us up, and we shall live in his sight. Then shall we know, if we follow on to know the LORD... (Hosea 6:2,3).
Just as it was through suffering (the loss of a rib) that Adam gained a bride, so through suffering the Messiah would gain his Bride.. all those who would believe on him. And as Adam was raised out of his sleep to enjoy Eve, so Christ was raised out of death to delight in his Bride.
And just as Esther saved her people, the Jews, by her willingness to die, so Christ saves his people by actually dying. As she suffered for three days and three nights of fasting (Esther 4:16) and then went into the secret place to intercede for her people, so Christ was in the grave three days and three nights before his ascension to intercede in Heaven for his people. And just as Esther was related both the to the Jews and the King (by marriage), so Christ is related both to us, being made a man, and to the Father, being of the same nature , God made flesh. And just as Esther had neither mother nor father, so Christ had neither father nor mother, his human nature having no human father, and his divine nature having no divine mother.
When Adam and Eve sinned God promised them a Saviour, Genesis 3:15, who would bruise Satan's head but be bruised in the heal himself in the process. It was by faith in this promise of God that those before the time of Abraham were able to be saved, and call upon the name of the LORD.
Abraham was promised that this Saviour would be one of his descendants. And Abraham believed God's promises and this was what made Abraham righteous before God. His faith in a coming Saviour made him righteous before God. And, as a token of the covenant He made with Abraham, God gave him the sign of circumcision to him and his descendants. God was pleased with Abraham because of Abraham's faith which he had before he was circumcised. Circumcision, then, was not what made Abraham pleasing to God, it was his faith (Gen 15:6).
David was promised one of his descendants would sit on his throne forever:
And when thy days be fulfilled, and you shall sleep with your fathers, I will set up your seed after you, which shall proceed out of your bowels, and I will establish his kingdom. He shall build a house for my name, and I will establish the throne of his kingdom forever. (2 Samuel 7:12-13).
This King would be from David's own body. He would live forever. No one today, in fact no one since the destruction of the Jewish public records in Jerusalem by the Romans (in either the first of second century), can actually prove they are a descendant of David.
David prophesied: "The stone the builders rejected has become the head of the corner" (Psalm 118:12) ie the builders are the Jewish religious authorities: the one rejected by them would be the Messiah.
Isaiah tells us that "a virgin will conceive and bear a son and his name shall be called Immanuel which means 'God with us'". (Isaiah 7:14)
Isaiah also tells us a child will be born "And his name will be called... Mighty God". (Isaiah 9:6)
Isaiah also tells:
He is despised and rejected by men, a man of sorrows and acquainted with grief. And we hid as it were our faces from him; he was despised, and we did not esteem him.
Surely he has borne our griefs and carried our sorrows; yet we esteemed him stricken, smitten of God and afflicted.
But he was wounded for our transgressions, bruised for our iniquities; the chastisement of our peace was upon him and with his stripes we are healed.
All we like sheep have gone astray, we have turned ereryone to his own way; And the LORD has laid on him the iniquity of us all.
He was oppressed and he was afflicted, yet he opened not his mouth; he was led as a lamb to the slaughter, and as a sheep before its shearers is silent so he opened not his mouth.
He was taken from prison and from judgement, and who will declare his generation (offspring)? For he was cut off from the land of the living; for the transgression of my people was he stricken.
And they made his grave with the wicked - but with the rich in his death, because he had done no violence, nor was any deceit in his mouth.
Yet it pleased the LORD to bruise him; he has put him to grief. When you make his soul an offering for sin, he shall see his seed, he shall prolong his days [ie he shall be resurrected after his suffering], and the pleasure of the LORD shall prosper in his hand. He shall see the travail of his soul [ie he shall see the souls saved as a consequence of his death, because he will be resurrected] and be satisfied.
By his knowledge my righteous servant shall justify many, for he shall bear their iniquities.
Therefore will I 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 53:3-12)
Isaiah also tells us what God said to his Messiah:
It is too small a thing that you should be my servant to raise up the tribes of Jacob, and to restore the preserved ones of Israel; I will also give you to be a light to the Gentiles; that you should be my salvation to the ends of the earth. (Isaiah 49:6).
And David prophesies, speaking of the Messiah's death:
They have pierced my hands and my feet. (Psalm 22:16)
This reading is the reading of Psalm 22:16 in the Dead Sea Scrolls. The Hebrew of the Masoretic Text translates as "Like a lion are my hands and my feet", which makes very little sense. Either the text was changed to "they have pierced" before the time of Christ or the Masoretic Jews changed it to "like a lion" sometime between 100 BCE and 1000 CE. The Christian view makes most sense, the Jews changed it because they didn't like "they have pierced my hands and my feet" because it points to Jesus of Nazareth as the Messiah.
Daniel tells us that after the Messiah has come the city [of Jerusalem] and the Temple will be destroyed, and this shall be until the consummation [until the day of judgement] (Daniel 9:26-27). In other words the Temple will never be rebuilt: the sacrificial system of the Tanakh is no longer needed because the True Sacrifice, the Messiah, has been sacrificed. As you know the Temple in Jerusalem was destroyed in 70 CE. So we need to find the Jewish Messiah before 70 CE.
Daniel tells us the Son of Man shall come in the days of the Empire of iron, the Roman Empire (Daniel 7:13,14).
In fact, Daniel tells us that 490 years after a decree to rebuild Jerusalem shall six very important things happen (Daniel 9:24). The decree of Artaxerxes (in Ezra 7) was given in 458 BCE. And 490 years after 458 was 33 CE when Christ was crucified. (And ss Rodger C. Young and Pastor Steve Rudd, (www.bible.ca) have discovered, using the Gregorian calendar it is 490 years from the day Ezra departed on 3rd April 458 BCE (Ezra 7:9) to the day of the resurrection 3rd April 33 CE to the exact day: this uses the dates as produced by the standard work on chronology for the period, Parker and Dubberstein's book "Babylonian Chronology 626 BC to AD 75".)
So, Daniel 9:24 is not directly pointing to the crucifixion: rather, it is pointing to the resurrection, as the sign demonstrating the efficacy of the crucifixion.
Finally, after three days and three nights Jonah was spewed out of the great fish/whale. He then went to Ninevah to tell them that in 40 days they were going to be destroyed. It is not correct to say he told them to repent. They asked him how he smelt so bad of fish, and maybe why he looked so strange, having been in a fish's belly for three days. He told them what had happened to him and why he had been in the fish... because of his rebellion against his God. We know the Ninevites learned these things about Jonah because "Jonah was a sign to the Ninevites" (Luke 11:30), meaning a sign of death and resurrection.
The Ninevites said: we are in big trouble. Yet Jonah found mercy at the last hour by his repentance. It won't do us any harm to repent either. Who knows? Maybe God will have mercy upon us too, even though God has not promised mercy upon our repentance. So they repented, and God relented. For the Jews, it is the eleventh hour: but God, the God of Abraham, Isaac and Jacob, offers forgiveness upon your faith in Jesus Christ and repentance back to God.
Jesus of Nazareth fulfills Daniel 9:26: he came before the destruction of the Temple. He fulfills Isaiah 49:6 because he is worshipped throughout the world as the Messiah. And he fulfills 2 Samuel 7:13,14 both through his mother (Luke's Gospel) and through his adopted father (Matthew's Gospel).
Both Luke and Matthew must have examined the public records in Jerusalem showing the ancestry of Jesus: the only thing Jesus's enemies, the Jewish religious authorities, had to do to show Jesus was not the promised Messiah was to demonstrate from those records that he was not a descendant of David. In that they never made that claim, and we instead only hear a deafening silence from them in this matter, then a very likely scenario is that they did indeed examine those public records and found precisely the same evidence as that found by Matthew and Luke.
Jesus of Nazareth is the Messiah of the Tanakh, he rose from the dead the third day as the Tanakh prophesied.