As one reads further and deeper into this diverse Reformed Tradition, the more damnable wickedness is discovered. And speaking of damnable wickedness, Berkhof details certain “Historical Views respecting the Necessity of the Atonement” (p. 368):
“THAT IT WAS RELATIVELY OR HYPOTHETICALLY NECESSARY.
Some of the most prominent Church Fathers, such as Athanasius, Augustine, and Aquinas, denied the absolute necessity of the atonement and ascribed to it merely a hypothetical necessity. Thomas Aquinas thus differed from Anselm on the one hand, but also from Duns Scotus on the other hand. This is also the position taken by the Reformers. Principal Franks says that Luther, Zwingli, and Calvin all avoided the Anselmian doctrine of the absolute necessity of the atonement, and ascribed to it only a relative or hypothetical necessity, based on the sovereign free will of God, or in other words, on the divine decree. This opinion is shared by Seeberg, Mosley, Stevens, Mackintosh, Bavinck, Honig, and others. Cf. also Turretin, on The Atonement of Christ, p. 14.
‘It deeply concerned us, that He who was to be our Mediator should be very God and very man. If the necessity be inquired into, it was not what is commonly called simple or absolute, but flowed from the divine decree, on which the salvation of man depended. What was best for us our Merciful Father determined.’ 
The atonement was necessary, therefore, because God sovereignly determined to forgive sin on no other condition. This position naturally served to exalt the sovereign free will of God in making provision for the redemption of man. Some later theologians, such as Beza, Zanchius, and Twisse, shared this opinion, but according to Voetius the first of these changed his opinion in later life” (Louis Berkhof, Systematic Theology p. 369).
 John Calvin, Institutes, 2.12.1
The Reformed Tradition claims to follow Scripture alone, in spite of their desecration of the blood of Jesus Christ. They do this wickedness under cover of “[exalting] the sovereign free will of God” in His divine decree. Here is John Owen — yet another despiser of Christ’s blood — contentedly citing a facinorous “Father”:
“…and in the meantime rest contented in that of Augustine: ‘Though other ways of saving us were not wanting to his infinite wisdom, yet certainly the way which he did proceed in was the most convenient, because we find he proceeded therein'”(John Owen, The Death of Death, p. 93; underlining mine).
The audacious Augustine using God’s “infinite wisdom” as a pernicious pretext for profaning the propitiatory blood of Jesus Christ (cf. Romans 3:25-26).
“Declare and bring near; yea, let them consult together. Who has revealed this of old; [who] has told it from then? Is it not I, Jehovah? And there [is] no God other than Me; a just God and a Savior; [there is] none except Me” (Isaiah 45:21).
A just God and a Savior. What, pray tell, would be another way of saving “not wanting to his infinite wisdom”? Augustine (& those believing like him) is an enemy of the cross who has not in mind the things of God, but the things of men.
This denial of the absolute necessity of the efficacious atonement of Jesus Christ is just one particular shade of Reformed Orthodoxy (“Reformed Orthodoxy” is not to be confused or confounded with Biblical Orthodoxy).
Not everyone who might arguably fit within this Reformed Brotherhood (a brotherhood that extends back to at least the days of Augustine) have confessed this particular form of execrable idolatry.
While it is true that all within this diverse Reformed Tradition confess damnable heresy, it is not true that they all confess the same damnable heresy. For instance, Charles Hodge spiritually-fornicated with an obvious God-hater in Friedrich Schleiermacher; and Hodge also denied the absolute sinlessness of Jesus Christ (see HERE and HERE for documentation). Who in the broad Reformed Tradition commit such blatant, knowing, deliberate, and brazen fornication as Charles Hodge did with Schleiermacher? Other than perhaps, a young and impressionable Machen with Wilhelm Herrmann?
A definition of a “characteristic”:
“A feature that helps to identify, tell apart, differentiate, or describe recognizably; a distinguishing mark or trait…A DISTINCTIVE.”
So, a Reformed doctrinal distinctive? A Reformed consensus? Some doctrine that characterizes ALL Reformed persons without exception? In addition to distinctive Reformed doctrine would be a distinctive component, feature, mark, or trait of a very specific type of “tolerance” that has its counterpart in such places as Genesis 3:4 (ye shall not surely die), Jeremiah 23:17, Ezekiel 13:9-16, and 2 John 9-11.
Charles Hodge and Gresham Machen do NOT espouse or confess Biblical Orthodoxy concerning the efficacious atonement of Christ. And whatever “‘essential’ Reformed doctrines” they do profess adherence to are obliterated to an “optional” status at best by their shameless whoring with those walking after the imagination of their own hearts.
“They say still unto them that despise me, The LORD hath said, Ye shall have peace; and they say unto every one that walketh after the imagination of his own heart, No evil shall come upon you” (Jeremiah 23:17).
“My hand shall be against the prophets who see vanity, and who divine a lie. They shall not be in the assembly of My people, and they shall not be written in the writing of the house of Israel, and they shall not enter into the land of Israel. And you shall know that I [am] the Lord Jehovah. Because, even because they made My people go astray, saying, Peace! and there [was] no peace. And he builds a wall, and, behold, [others] daubed it [with] lime. Say to those daubing [with] lime, Yea, it will fall. There will be a flooding rain; and you, O hailstones, shall fall, and a tempestuous wind shall break. And, behold, when the wall has fallen, it shall not be said to you, Where [is] the daubing with which you have daubed? So the Lord Jehovah says this: I will even break in My fury [with] a tempestuous wind. And there shall be a flooding rain in My anger, and hailstones in fury, to consume it. And I will break down the wall that you have daubed [with] lime and bring it down to the ground; yea, I will bare its base. And it shall fall, and you will be consumed in its midst. And you shall know that I [am] Jehovah. And I will complete My wrath in the wall, and in those who daubed it [with] lime. And I will say to you, The wall [is] not; and, Those who daubed [are] not. The prophets of Israel who are prophesying concerning Jerusalem, and who see visions of peace for her, even [there is] no peace, declares the Lord Jehovah” (Ezekiel 13:9-16).
“Everyone transgressing and not abiding in the doctrine of Christ does not have God. The [one] abiding in the doctrine of Christ, this one has the Father and the Son. If anyone comes to you and does not bear this doctrine, do not receive him into the house, and do not speak a greeting to him. For the [one] speaking a greeting shares in his evil works” (2 John 9-11).
Speaking peace apart from the only ground of peace is not a Reformed (or Calvinist) distinctive. For many other tolerant professing Christians who are not “Calvinist” or “Reformed,” commit this spiritual fornication also.