This is what the Bible teaches:
Phil. 2:5 Keep this mental attitude in you that was also in Christ Jesus, 6 who, although he was existing in God’s form, did not even consider the idea of trying to be equal to God. 7 No, but he emptied himself and took a slave’s form and became human. 8 More than that, when he came as a man, he humbled himself and became obedient to the point of death, yes, death on a torture stake. 9 For this very reason, God exalted him to a superior position and kindly gave him the name that is above every other name, 10 so that in the name of Jesus every knee should bend—of those in heaven and those on earth and those under the ground— 11 and every tongue should openly acknowledge that Jesus Christ is Lord to the glory of God the Father.
Evidently: God exalted Jesus. Who's that God?
Acts 3:13 The God of Abraham and of Isaac and of Jacob, the God of our forefathers, has glorified his Servant, Jesus, whom you handed over and disowned before Pilate, even though he had decided to release him.
Who is the God of Abraham and of Isaac and of Jacob, the God of the forefathers of the Jews?
John 8:54 Jesus answered: “If I glorify myself, my glory is nothing. It is my Father who glorifies me, the one who you say is your God.
Is Jehovah, the Father and God of Jesus, only the God of the Jews?
Rom. 3:29 Or is he the God of the Jews only? Is he not also the God of people of the nations? Yes, also of people of the nations. 30 Since God is one, he will declare circumcised people righteous as a result of faith and uncircumcised people righteous by means of their faith.
Did Christians in the first century know Jehovah? Of course, they were mostly Jews. They made this prayer to Jehovah:
Acts 4:24 (...) “Sovereign Lord, you are the One who made the heaven and the earth and the sea and all the things in them, 25 and who said through holy spirit by the mouth of our forefather David, your servant: ‘Why did nations become agitated and peoples meditate on empty things? 26 The kings of the earth took their stand and the rulers gathered together as one against Jehovah and against his anointed one.’ 27 For truly both Herod and Pontius Pilate with men of the nations and with peoples of Israel were gathered together in this city against your holy servant Jesus, whom you anointed, 28 to do what your hand and counsel had determined beforehand to occur. 29 And now, Jehovah, give attention to their threats, and grant to your slaves to keep speaking your word with all boldness, 30 while you stretch out your hand for healing and while signs and wonders occur through the name of your holy servant Jesus.”
If Jehovah was the God of first century Christians, who do you think Jesus was to them? ;)