What is the authenticity of the Hadith: "Whoever says 'There is no god but Allah' shall enter Paradise," and does it have the continuation, "even if he commits adultery and even if he steals"? And is merely uttering and believing sufficient for entering Paradise?

The absolute hadiths which indicate that whoever's last words were " La ilaha illa Allah " (there is no god but Allah) entered Paradise, or whoever died without associating anything with Allah entered Paradise, must be understood in conjunction with the restricted hadiths that explain them. It is essential to disbelieve in everything worshipped besides Allah, and the two testimonies of faith (Shahadatayn) must include knowledge of their meaning and acting upon their implications, inwardly and outwardly, with certainty, truthfulness, sincerity, acceptance, submission, and love for Allah, for the word, and for its people. Merely uttering the two testimonies without the heart's conviction and acting upon their meaning is insufficient.