Okay, so say Hitler accepts that baptism. And Hitler accepts that sealing. Now, let’s compare that to my father. He was sealed to my mom, and got his temple recommend renewed on his hospice bed. He was buried in his temple garments, and has an image of Moroni on his headstone. But he smoked until he was too weak to hold up his cigarette. He openly, and flagrantly violated the Word of Wisdom during his entire adult life. Technically, he obtained his recommend fraudulently because he continued to smoke. My brother was baptized at 8 and sealed to my parents, as was I, in 1988. He committed suicide.
According to Mormon doctrine, if Hitler accepts his baptism and ordinances in Spirit Prison, he can go to the Celestial Kingdom. However, my brother and father, being baptized LDS in life, have no opportunity to have those sins washed away in death, and being given the fullness of the gospel while they were here on earth, they are condemned to the Telestial or Terrestrial Kingdom. According to the Mormon doctrine, I have committed an act worth of excommunication by being baptized in the Catholic church, and my fate will be similar to my brother and father.
According to Catholic doctrine, as far as I can tell, while my brother’s sin was grievous, it was done while not in a proper state of mind and he may not be held culpable. And while my father was never Catholic, he did die living his best life that he could in the way that he thought that Christ wanted him to live his life. I can pray for their holy souls in Purgatory, which I do on a daily basis. And in both cases, Christ’s mercy can most definitely apply even though they were not Catholics.