Jhn 3:17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
Jhn 3:18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
Why do you think Catholics do not know what John 3:16 means? Are you going by your own experience when you were a so-called Catholic? How do you know what is in the heart or mind of any Catholic?