What does it mean to have a moral obligation.
It means that a failure to act constitutes a sin of some type, probably grave. These would be sins of omission.
For example. Failing to go to Sunday Mass is a sin of omission.
A better example is raising our children. We are morally obligated to see that our children have as good of an upbringing, including a Catholic education, as possible. Suppose a parent sends their kids to Catholic school, but otherwise ignores them. The parent is just too interested in his/her own personal pleasures and pursuits to give his/her children attention, love or guidance. This parent is ignoring their children and may be morally culpable for not properly raising their children.
Ahhhh! Thank you, that is very enlightening. I see things a little more clearly now. Does morally culpable mean sinning?
In the way I used it, yes, but in a larger sense. Larger in that multiple individual sins may be involved which may include sloth, selfishness, lack of charity, pride, etc.