Not Opposing Abortion Forcefully Enough

I do not think you should confess this unless there was a particular, individual instance at least when you did not do what you could. This should be concrete, not general. Otherwise, we could get ourselves into a state about all the evils that we are not doing enough to stop. All of us could do more for world peace or for the family or for the poor and so on, but there is not clearly a sin unless we refuse an opportunity where in justice we should have acted concretely in our own circumstances.

So, for example, if you hear some coworkers discussing whether one of them should have an abortion, and you do not say anything to encourage the protection of life, then you certainly should confess that; but if you have not volunteered for the local pro-life ministry when you could, it is not necessarily a sin if you have other good works you are doing.