Immaculate conception=Mary sinless
Romans 3:23=all have sinned
Next question please?
All of who?
No, that is a primitive and mindless reading of the psalm quote. To take this psalm literally -- or think that st. Paul quoted it thinking of it as a literal definition of everyone would mean that not only Mary sinned (the Bible does not record any such), but she also does not seek God and is quick to murder. So is your pastor: God-hater and murderer. Enjoy your fantastical theology; I'll stick with both the Holy Scripture and my Church explaining it.