They don’t get it.
They don’t understand the heart change that occurs in the born again believer cause they’ve never experienced it.
They think that believer think *Oh goodie, I am secure in my salvation. That means that I can go out and sin all I’d like with no consequences* because that’s what they’d think if they thought they were secure in their salvation and there wer no restrictions on their behavior.
What motivates them to not sin isn’t love for and gratitude to God but fear of hell.