So then, the question is: "Are there essential doctrines that one must adhere to in order to be a Christian, and if so, what are they?"
ACTS 2:
22 .......listen to these words: Jesus the Nazarene was a man who was shown to you by God with power, omens, and signs that God performed through him in your midst, as you already know. 23 Yes, you gave this person (who received his advice and his ability to see the future from God) over to the hands of men who were without Law, and you nailed him up. 24 But God
resurrected him, freeing him from the cords of death, because it wasn’t possible for [death] to hold him.
25 ‘Then David said this about him:
I‘ve put Jehovah always before me.
And since He is at my right hand,
I will never be shaken.
26 For, in my heart I am cheerful,
And with my tongue I rejoice;
So my body will rest in that hope.
27 You won’t abandon me in the grave,
And You’ll not allow Your loyal one to see corruption.
28 For, the ways of life You have shown me,
And You’ll fill me with joy from Your face.’
29 ‘Men! Brothers! It’s good to speak to you openly about the patriarch David, for he died, was buried,
and his tomb is still with us to this day. 30 Yet, he was a Prophet, and he knew that God had sworn an oath to him that He would put someone on his throne who was the fruit of his loins. 31 So, [David] looked into the future and spoke about the resurrection of the
Anointed One… that he wouldn’t be abandoned in the grave and that his flesh wouldn’t see corruption.
32 ‘Then this Jesus was resurrected by God, and we are all witnesses to that… 33 he was lifted to God’s right hand, where he received the Holy Breath (which the Father had promised). And he’s the one who has poured out all of this that you’re seeing and hearing.
34 ‘Now,
David didn’t go to heaven, but he said:
Jehovah</SPAN> said to my Lord;
Sit down at my right hand
35 Until I set your enemies as a stool for your feet.
36 So, let the entire House of IsraEl know for sure that God made this Jesus whom you impaled the Lord and Anointed One!
I think this explanation given by Peter says it better than anyone of us ever could.