What makes you think Die Linke gave up their "religion"? I don't see any indication of such a conversion in either the Party's saying or doing. The same claim was made about other communist parties, e.g. "Vänsterpartiet" in Sweden which translates to "The Left Party" (they're even walking in step when it comes to choosing new labels) but it doesn't take much (or any, really) effort to pierce that veil.

I don't believe they gave up Marxism-Leninism, they just gave the monster a new name and claim it is nothing like its predecessor. They do that a lot, changing the label on the package. Inside it is still the same monster, waiting to be unleashed.