Cú Chulainn

'Religion is the general theory of this world, its encyclopaedic compendium, its logic in popular form, its spiritual point d’honneur, its enthusiasm, its moral sanction, its solemn complement, and its universal basis of consolation and justification.' Karl Marx

'Religion is the fantastic realization of the human essence since the human essence has not acquired any true reality.' Karl Marx

'Religious suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions.' Karl Marx

So whenever someone quotes Marx's 'Religion is the opium of the people' they should be putting it in context with the sentences above which precede that sentence and clarify his position.

beginning with "Yet anybody..." is your thought not that of Marx. And no, Marx, against the Marxists, did not imagine real happiness comes from looting. opium has a positive sense, as a consolation, and a negative one, as a retreat from reality

This is Marx after the opium part: "The abolition of religion as the illusory happiness of the people is the demand for their real happiness." Putting it in context with what comes before, we can see this is only one point among many more.