Heresy is defined by being new — it can’t be traced back to the beginning

I am accustomed in my prescription against all heresies, to fix my compendious criterion (of truth) in the testimony of time; claiming priority therein as our rule, and alleging lateness to be the characteristic of every heresy. This shall now be proved even by the apostle, when he says: “For the hope which is laid up for you in heaven, whereof ye heard before in the word of the truth of the gospel; which is come unto you, as it is unto all the world.” For if, even at that time, the tradition of the gospel had spread everywhere, how much more now! Now, if it is our gospel which has spread everywhere, rather than any heretical gospel, much less Marcion’s, which only dates from the reign of Antoninus, then ours will be the gospel of the apostles.  But should Marcion’s gospel succeed in filling the whole world, it would not even in that case be entitled to the character of apostolic.

Tertullian
The Five Books Against Marcion, Book V
Chapter XIX

Marcion preached only a resurrection of the soul

For Marcion does not in any wise admit the resurrection of the flesh, and it is only the salvation of the soul which he promises; consequently the question which he raises is not concerning the sort of body, but the very substance thereof. Notwithstanding, he is most plainly refuted even from what the apostle advances respecting the quality of the body, in answer to those who ask, “How are the dead raised up? with what body do they come?” For as he treated of the sort of body, he of course ipso facto proclaimed in the argument that it was a body which would rise again.

Tertullian
The Five Books Against Marcion, Book V
Chapter X

The sacrament as Christ’s body and blood is denied by the heretics

In like manner, when treating of the gospel, we have proved from the sacrament of the bread and the cup the verity of the Lord’s body and blood in opposition to Marcion’s phantom;

Tertullian
The Five Books Against Marcion, Book V
Chapter VIII

The heretics claim souls are created by angels and preexist the body

Some suppose that they came down from heaven, with as firm a belief as they are apt to entertain, when they indulge in the prospect of an undoubted return thither. Saturninus, the disciple of Menander, who belonged to Simon’s sect, introduced this opinion: he affirmed that man was made by angels.

…Now, to procure belief in all this—that the soul had formerly lived with God in the heavens above, sharing His ideas with Him, and afterwards came down to live with us on earth, and whilst here recollects the eternal patterns of things which it had learnt before—he elaborated his new formula, μαθήσεις ἀναμνήσεις, which means that “learning is reminiscence;” implying that the souls which come to us from thence forget the things amongst which they formerly lived, but that they afterwards recall them, instructed by the objects they see around them. Forasmuch, therefore, as the doctrines which the heretics borrow from Plato are cunningly defended by this kind of argument, I shall sufficiently refute the heretics if I overthrow the argument of Plato.

…Amongst so many nations, in so great a crowd of sages, Plato, to be sure, is the only man who has combined the oblivion and the recollection of ideas. Now, since this main argument of his by no means keeps its ground, it follows that its entire superstructure must fall with it, namely, that souls are supposed to be unborn, and to live in the heavenly regions, and to be instructed in the divine mysteries thereof; moreover, that they descend to this earth, and here recall to memory their previous existence, for the purpose, of course, of supplying to our heretics the fitting materials for their systems.

Tertullian
A Treatise on the Soul
Chapter XXIII and XXIV

The Lutherans saw their movement as not having introduced any innovations but only correcting abuses

Inasmuch, then, as our churches dissent in no article of the faith from the Church Catholic, but only omit some abuses which are new, and which have been erroneously accepted by the corruption of the times, contrary to the intent of the Canons, we pray that Your Imperial Majesty would graciously hear both what has been changed, and what were the reasons why the people were not compelled to observe those abuses against their conscience.

Augsburg Confession
Article XXI.X

Luther viewed himself as not bound by any form of Church authority

“I answer”, replied Luther, “that God once spoke through the mouth of an ass. I will tell you what I think. I am a Christian theologian and I am bound not only to assert but to defend the truth with my blood and death. I want to believe freely and to be a slave to no one, whether a council, university, or pope. I will confidently confess what appears to me to be true, whether it has been asserted by a Catholic or a heretic, whether it has been approved or reproved by counsel.”

Martin Luther
The Leipzig Debate, 1519

Atheism really is a belief system

In speaking of the fear of religion, I don’t mean to refer to the entirely reasonable hostility toward certain established religions… in virtue of their objectionable moral doctrines, social policies, and political influence. Nor am I referring to the association of many religious beliefs with superstition and the acceptance of evident empirical falsehoods. I am talking about something much deeper – namely the fear of religion itself… I want atheism to be true and am made uneasy by the fact that some of the most intelligent and well-informed people I know are religious believers. It isn’t just that I don’t believe in God, and naturally, hope there is no God. I don’t want there to be a God; I don’t want the universe to be like that.

Thomas Nagel
The Last Word

Science does not have the right to give to me my reason for being. But I am going to take science’s view because I want this world not to have meaning. A meaningless world frees me to pursue my own erotic and political desires.

Aldous Huxley
Ends and Means

The definition of a heretic

…a heretic may from his case be designated as one who, forsaking that which was prior, afterwards chose out for himself that which was not in times past. For in as far as what was delivered in times past and from the beginning will be held as truth, in so far will that be accounted heresy which is brought in later.

Tertullian
Five Books Against Marcion, Book I
Chapter I

Heretics don’t follow the same practices and can be refuted therefore without the scriptures

These evidences, then, of a stricter discipline existing among us, are an additional proof of truth, from which no man can safely turn aside, who bears in mind that future judgment, when “we must all stand before the judgment-seat of Christ,” to render an account of our faith itself before all things.

On the present occasion, indeed, our treatise has rather taken up a general position against heresies, (showing that they must) all be refuted on definite, equitable, and necessary rules, without any comparison with the Scriptures.

Tertullian
Against Marcion
The Prescription Against Heretics
Chapter XLIV