Quicksand in common, together as yet uncircumcised Jeremiah. 4.3-4.

The Divine Fellowship of Being - Father, Son and Spirit, the three-in-oneness of the Godhead - commonly called the Trinity

God, His Spirit and His Word each active participants in Creation Gen.1.1-3.
Divine Council in Creation of man, in the banishment and in the destruction of Babel. Gen.1.26, 3.22 ,11.7.
Compound Unity of Divine Essence Gen.11.1, Deut.6.4.
Distinction between the Messenger of Yahveh, identified as Yahveh, and Yahveh the Sender. Gen.18.1,13,17,22,33 Gen. 19.24 and many other texts.
The Unseeable Yahveh is seen, worshipped, talked to, eaten with, felt and wrestled with in the Person of His messenger. Exod 33.20 Gen.17,18, 32.30 etc..
Who is this but His Word? - which is precisely what Messiah confirms John .8.56.

Eternal Origin of the Son of God

The Eternal wisdom of God 'begotten' (khololti) before and joyful participation in Creation Prov.8.24,22-23.
The Son's omnipotent engagement in works of God, ascent and descent. Prov. 30.4.
The goings forth of the Ruler to come from Bethlehem from everlasting (perpetual days) Micah 5.8.
'Thou art My Son', though His second begetting (from death) is ascribed to a day.Ps.2.7.
Job sees that His kinsman-Redeemer/Avenger (Goel) lives! Job.19.25.

Divine Personality of the Holy Spirit

The Holy Spirit sore vexed. Isa.63.10
The Spirit of God the cause of Israel's rest Isa.63.14
The immediate source of courage, counsel, wisdom, repentance, prayer and victory. 1 Sam.11.6,16.13, 1 Ki. 22.24, Zech.12.10, Zech.4.6.

Original sin

Flattery will not do! Faithful prophets didn't plaster over these matters!

God looked down from heaven upon the children of men, to see if there were any that did understand, that did seek God.
Every one of them is gone back: they are altogether become filthy; there is none that doeth good, no, not one.

The impotent depravity of the will

Puppets of Satan and the flesh by nature: Isa.59.2-15

But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear.
For your hands are defiled with blood, and your fingers with iniquity; your lips have spoken lies, your tongue hath muttered perverseness.
None calleth for justice, nor any pleadeth for truth: they trust in vanity, and speak lies; they conceive mischief, and bring forth iniquity.
They hatch cockatrice’ eggs, and weave the spider’s web: he that eateth of their eggs dieth, and that which is crushed breaketh out into a viper.
Their webs shall not become garments, neither shall they cover themselves with their works: their works are works of iniquity, and the act of violence is in their hands.
Their feet run to evil, and they make haste to shed innocent blood: their thoughts are thoughts of iniquity; wasting and destruction are in their paths.
The way of peace they know not; and there is no judgment in their goings: they have made them crooked paths: whosoever goeth therein shall not know peace.
Therefore is judgment far from us, neither doth justice overtake us: we wait for light, but behold obscurity; for brightness, but we walk in darkness.
We grope for the wall like the blind, and we grope as if we had no eyes: we stumble at noonday as in the night; we are in desolate places as dead men.
We roar all like bears, and mourn sore like doves: we look for judgment, but there is none; for salvation, but it is far off from us.
For our transgressions are multiplied before thee, and our sins testify against us: for our transgressions are with us; and as for our iniquities, we know them;
In transgressing and lying against the LORD, and departing away from our God, speaking oppression and revolt, conceiving and uttering from the heart words of falsehood.
And judgment is turned away backward, and justice standeth afar off: for truth is fallen in the street, and equity cannot enter.
Yea, truth faileth; and he that departeth from evil maketh himself a prey: and the LORD saw it, and it displeased him that there was no judgment.

The incarnation of God's Word

God's Covenant messenger - Yahveh in the flesh. Mal.3.1, Gen.17,18,

The same is worshipped and adored as God -Gen.18.2 (3 messengers, only one bowed to and addressed as Lord (majestic plural of Lord (Adonai), singular suffix to 'thy eyes' and the rest of the clause)),
Josh.5.14 - in a way that is utterly immoral and wrong for any created being (Ex 34.14, Isa.14.14).

The virgin birth of the eternal Son, who is described as the Mighty God - a title otherwise reserved for YHWH

Isa. 7.14 A most distinctive 'sign', both from Heaven and on Earth - its manifestation denied to Ahaz for his unbelief.

The word Almah may certainly be used of a virgin (Ge 24.43), and the usually more distinctive word for virgin Betulah is once used of a married woman (Joel 1.8),
presumably because of the recent loss of her virginity.
This mysterious child Emmanuel is the One to Whom the land itself belongs Isa.8.8 and 10.
This same Son, spoken of as being wonderfully given at the time of Israel's future deliverance, Isa. 9.6-7 (5-6 in Hebrew text, the words are identical)

For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called
Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.

Covenant headship

There are two aspects to this same doctrine:
First the Fall of all men in the Fall of Adam, since a covenant was broken by him, who was a federal head - Hosea 6.7 ('like Adam'), Isa 48.8, Ps.58.2.
Second the headship of the true David, 'the Beloved', (Ps.89.1-3, Isa 55.1-4), in a redemptive covenant, both like (in constitution) and unlike (in moral effect) the first,
by which spiritual circumcision is administered (Ezek.37.24-26, Jer 4.4, Ezek.44.9), sin no longer imputed (Ps.32.1, Isa 54.6-10),
and on the basis of His vicarious atonement in blood (Ex 24.8, Zech.9.11 - the suffix is feminine indicating that the covenant is made with Zion's daughter).

The absolute necessity of a blood atonement for sin

This is often strongly contested by Orthodox Jews today on the basis of texts like Ps.40.6 and Hosea 6.6, in the light of the Divinely ordained loss of the Temple,
Toviah Singer for example claims repentance and good works are a sufficient substitute.
Each of these texts speak of the insufficiency of a blood sacrifices by itself without true repentance. Psalm 51.16 speaks of a sin so egregious that Levitical atonement could not remove it.
The fact remains that as Michael Brown has well argued in some detail on the subject, the shedding of blood is essential for true atonement, see Numbers 25.13, 2 Samuel 24.25,
For ' it is the blood that maketh an atonement for the soul.' Leviticus 17.11

Even some Orthodox Jews recognise this and offer up an unscriptural and diminutive chicken sacrifice (kapporot) near Yom Kippur, in the face of the devastating loss of the Levitical covenant in blood.
These words are reportedly said, 'This is my exchange, this is my substitute, this is my atonement.
This rooster/hen will go to its death (or this money will go to charity), while I will enter and proceed to a good long life and to peace.'

The Muslim feast of Eid al Adha, the holiest day in Islam's calender is a pale reflection of Yom Kippur and also unconsciously provides a shadowy witness to this reality,
even though Muslims often deny the necessity of a blood atonement for sin - it also takes place on the 10th day of a lunar month.

Substitutionary atonement

When an offerer confesses his sin, lays his hands on the head of the animal to be offered then slits his throat and pours his blood before the altar,
who will deny that the animal has figuratively borne the punishment and curse of the offerer?
If the penalty of sin is, 'in the day you eat of it dying you shall die' how else can the sinner escape death but by the death of another to whom he is bound by covenant?
Was not this precisely what Moses and David requested, that they might be blotted out or die in place of the people they represented?

Note how the Lord presses Moses to intercede (Ex 32:10) and Moses block the way to their judgement with his own life Ex. 32.32,
2 Sam 24.17 (David's last recorded act in Samuel) 2 Sa 18:33 (on behalf of his vile son).
Why did God punish David's son for his trangression, (2 Sam.12.13-14) when he forbids earthly judges from the same (Deut 24.16)?
Note again how one man's death was taken as an atonement for many others. Num. 25.13-14.

The absolute exaltation and eternal sovereignty of the Messiah, in and to His Father's pleasure

For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder:
and his name shall be called Wonderful, Counsellor, The mighty God (rwbg la), The everlasting Father, The Prince of Peace.
Of the increase of his government and peace there shall be no end, upon the throne of David,
and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever.
The zeal of the LORD of hosts will perform this.
(Isa. 9.6-7 (5-6 in Hebrew))

A Psalm of David.
The LORD said unto my Lord, Sit thou at my right hand, until I make thine enemies thy footstool.
The LORD shall send the rod of thy strength out of Zion: rule thou in the midst of thine enemies. (Ps.110.1-2)

I will declare the decree: the LORD hath said unto me, Thou art my Son; this day have I begotten thee.
Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession.
Thou shalt break them with a rod of iron; thou shalt dash them in pieces like a potter’s vessel.
Be wise now therefore, O ye kings: be instructed, ye judges of the earth. (Ps.2.7-10)

The necessity of an immediate surrender to and worship of the Messiah for deliverance from sin

Serve the LORD with fear, and rejoice with trembling.
Kiss the Son, lest he be angry, and ye perish from the way,
when his wrath is kindled but a little. Blessed are all they that put their trust in him.
(Ps.2.10-11)
Hebrew translations differ, but the Aramaic word for 'Son' is also used in Solomon's Proverbs.

What is the circumcision of the heart needed by all?