Rashi on the opening pasuk of Bereishit cites the well-known midrash (Yalkut Shimoni 187) asking why the Torah begins with Creation and not with the giving of the first mitzvah. The answer given there, paraphrased, is that Hashem thereby establishes His authority to give the Land of Israel to His people, Israel. To anybody who wishes to lodge a competing claim, the response is that Hashem made the whole world and He can do with it as He sees fit.
Our haftara is staked on a similar premise. It is introduced as the message of “The G-d, Hashem, who creates the heavens and suspends them, He spreads the land and all that grows from it.” (Yeshayahu 42:5). Radak explains that the navi Yeshayahu is speaking of the eternal covenant of Hashem to a generation full of people who don’t believe in His power. They believe that the universe has been eternally present and was not created, or that material reality arose as a result of a series of happy accidents and that the world is very ancient. For this reason, the navi stresses that Hashem is creating the universe in the present tense – He created everything and He is creating it again in every moment. Therefore, he may surely promise whatever suits Him to those He finds worthy, and He will unfailingly deliver upon that promise.
Malbim explains that the navi is emphasizing the heavens and the earth because the improbable union of these two is an outcome of the manner in which Hashem created everything. One would not expect earth and heaven to remain locked together in just such a manner that enables life to flourish, and this has only been done for the purpose of allowing the human being to grow and to thrive in this environment. Humanity has been created, similarly, by uniting the higher and the lower forces. When Hashem brings heaven and earth together to create the world, He is effectively signing His Name upon Creation. Only one artist has the skill to bring opposites together for the purpose of making some new thing, and only one thing has ever been made that can be conscious of itself, of how it has been made and the world in which it lives.
The pasuk continues, describing the soul of a nation and the spirit of those who traverse the earth. Malbim explains that this introduces the next level of consciousness of the masterpiece of Hashem. Beyond the physical reality and what is apparent to the natural faculties, there is something remarkable that Hashem has also created. The human being in its natural state is not capable of seeing the higher truth that has been concealed behind the veil of reality, but when the universe and the humans who dwell in it achieve their consummation at the end of time, then this hidden level will be apparent as readily as the heavens and the earth are today. Malbim says this is the only fitting introduction to what follows in our haftara – a message intended for those who are to experience this consummation.