... or STrANgER IN A StRANgE LAnD as the title has it.
This is not Obama in London (today for the G20) but Robert Heinlein's novel first published in 1961 and then republished in 1991 at 220,000 words with all the cut bits restored.
Not wholly wise.
The plot concerns a child of the first Martian expedition, brought up by the Martians after the death of all the adults. The second expedition brings the child, Valentine Michael Smith, back to earth as a 25 year old man, heir to an immense fortune and legally perhaps the sovereign of Mars.
Smith is a classic literary type, the smart but totally innocent stranger in a strange land. Heinlein has a lot of fun using him as a mirror against American society. After an early thriller-sequence whereby Smith is extracted from Government control, he ends up at the ranch of another of Heinlein's stock characters, the elderly sage Dr Jubal Harshaw. This man: rich, a medical doctor, a top lawyer, an author and someone incredibly well-connected, is Heinlein's mouthpiece for his philosophy.
Like all Heinlein's novels, SIASL is incredibly didactic. His editors never seemed to have enough power to tell him to cut those 'tell-not-show' sections where Heinlein sounds off. The novel got into trouble on publication mostly for its attack on organised religion, the effectiveness of H.'s critique being that he simply tells it like it is: the true nature of charismatic cults; the viciousness and self-contradictions of The Bible; the gullibility of the marks, sorry, believers.
My main problem is not the religious critique - which I agree with, or even the way the Islamic character Dr. Mahmoud gets to be called "Stinky" (yeuk!). No, the problem is sex. Heinlein, although altogether in favour of science and technology, never thought to apply evolutionary thinking to people. In his mind, we are all blank slates written upon by an oppressive and strait-laced Abrahamic culture.
Remove this overlay and what do you get? An idealised society of love, bonded by unrelenting on-demand sex between all parties, without reluctance and certainly without jealousy. As the 'Man from Mars' eventually gets the hang of ('groks') the wrong nature of earthly society, his solution is to set up his own church-like outfit where the inner core get to learn to speak and think in the Martian language and have sex with each other all the time Bonobo-style*.
Nothing is described particularly graphically but that's not the problem. It's just that there's something particularly unsavoury about having to share in Mr. Heinlein's voyeuristic fantasies. I hate to use the term 'dirty old man' but there you are. Both wrong and distasteful.
It all ends with a bit of a laugh, as it it turns out that the afterlife exists after all, and that Valentine Michael Smith is the Archangel Michael, working alongside sundry other cult leaders who have been rubbished in the main text. Perhaps this is the final meta-satire.
Heinlein could certainly write, and for me his best book was Starship Troopers, still overly didactic but at least he confined his evangelism to the conditions of citizenship, where he was on safer ground.
* Apparently Bonobos don't have sex all the time for social bonding purposes - another myth shattered.