In 1841 Stirner joined Die Freien (The Free), a group of "left" or "young" Hegelians who gathered at Hippel's Weinstube in Berlin in the turbulent years from 1840 to 1845. The central figures, aside from Stirner, were Ludwig Feuerbach, Bruno Bauer, David Strauss and Arnold Ruge. Younger members were August von Cieszkowski, Karl Scmidt, Edgar Bauer, Friedrich Engels and Karl Marx.
The Young Hegelians were an intellectual group whose common theme was the ongoing application of Hegel's dialectical method rather than acceptance of Hegel's philosophical conclusions. This materialized in radical critiques of religion, the most known of which are David Strauss' Das Leben Jesu (The life of Jesus) and Ludwig Feuerbach's Das Wesen des Christentums (The Essence of Christianity).
Of primary importance in the Young Hegelian world-view was the belief that Hegel's dialectical method implied that world-history had gone through two antithetical stages; the feeling or materialism of antiquity, and later the modernist epoch of thought in Christianity, and that it was now the philosophers' task to move on to synthetical praxis. This is perhaps most clearly put forth in Cieszkowski's Prolegomena to Historiosophy. With these as their focal points, the Young Hegelians became notoriously politically radical. From Hegel's identification of the Real and the Rational, the Young Hegelians had gone on to a program to rationalize the real.
Spinoza basically said that God was a Pan, i.e. that he could be seen as Nature, as "us". Thus, I and You are in a deeper sense identical. This was a theme later taken up by Schelling, one of Hegel's philosophical forefathers. The other forefather was Fichte. Fichte took up on Kant's split between Mind and World, and tried to unite the two. For Fichte, all was "Ego". Not yours or mine ego, mind you, but a general and all-pervading Absolute Ego. When some one looked at the world, he was really looking at himself.
So both Fichte and Schelling tried to arrive at a unity, a non-dualism between Mind and Matter. What Hegel went on to do, was to declare both approaches to be still too "one-sided", trying to reduce either Mind to Matter (as in the case of Schelling) or Matter to Mind (as in the case of Fichte). For Hegel, Matter and Mind were both sides of The Absolute. In his synthesis, Hegel united religious thoughts as well as science. Philosophical development was the development through a dialectical process of Spirit.
At least so he thought. His disciples divided into two classes: The Old Hegelians, who meant that with Hegel, philosophical development had come to an end, and the Young Hegelians, who insisted in some way that one should "apply Hegel to Hegel", i.e. use Hegel's methodology to go beyond Hegel. It is the latter who are of interest.
David Strauss was the first to be noted. He used the method of Hegel to analyze the New Testament, and came to the conclusion that if God was such as theologists had spoken of Him, then it was patently absurd for it to be just one Christ. The New Testament Christ Jesus, he maintained, was no more than a metaphor for the real Christ, who was Mankind itself. Mankind was its own redeemer, for in its moral progress, the moral better would have to - and willingly did! - take the punishment for the sins of the old and morally inferior mankind.
Ludwig Feuerbach followed up on this, with his declaration that not only was Mankind Christ - it was also God. This was argued in his "The Essence of Christianity" - rather well so, I think - from that God is known through feeling [i.e. intuition]. But if feeling was from God, would not then feeling have to be Divine? Through a series of clever arguments, Feuerbach leads us to that what we mean by "God" and "Divine" is exactly the feeling of it. Part of the argument goes that a God without predicates is an empty subject, which has no demand for our attention. Only through His predicates does he have such a demand. And those are exactly those of the feeling of Divineness we have for this "God". A further argument leads us to that this feeling is really our own and - says Feuerbach - our essence in Man. The reverence we have for God is really reverence for Man the species and essence in ourself.
An important charge made by Feuerbach in another essay, on the reformation of Hegelian philosophy, was that Hegel had by no means gotten away from one-sidedness. Hegel had not taken into consideration sensuousness and the intellect. He had forgotten to tie down the Mind of the "Phenomenology of Spirit" to the bodily, thinking person.
It is this latter critique which Stirner follows up on. In "Stirner as Hegelian", Lawrence Stepelevich argues that much of Stirner can be understood as reading the Phenomenology with the new and improved view-point that the "we" there is really the one and concrete "I".
For Hegel, the Absolute is "the power of the negative", i.e. that which is not there in determination, but rather that which views and criticizes every determinate thought - i.e. the Subject. For Stirner, this critic, this "power of the negative" is the single consciousness - himself, the individual. This is the meaning of Der Einzige.
But it is with Mind as something other than oneself that also the Young Hegelians take off. August Cieszkowski reforms Hegel's world history to fit better with the Hegelian form of philosophy, and divides it into Past, Present and Future. Cieszkowski argues that we have gone from Art (the Past), which was a stage of contemplating the Real, to Philosophy (the Present), which is a contemplation of the Ideal, and that since Hegel's philosophy was the summing-up and perfection of Philosophy, the time of Philosophy was up, and the time for a new era has dawned - the era of Action.
But Cieszkowski made this call for action with the Mind seen as an Other. What else could result when the Action and the Will was in the Other, than a "should". Not an "I will", but an "I should". And the later Young Hegelians followed him up on that. Even for Feuerbach, the self was in the species, not in the single man. Thus came the call to realize one's species-nature. The belief that our "essence" resided in the collective gave - as it necessarily must - rise to a "shall" which you are not to dispose of at your will.