In another thread I remarked that I admired the Catholic church's steadfastness in adhering to some hard truths - and sometimes, as I know personally, it "gets in the way" of pursuing a reconciliation with the Catholic church.
Marriage
In my case it's a divorce and remarriage issue - and I didn't exactly see this until various states began legalizing gay and lesbian marriages. I mentally fulminated about it, certain of the sinfulness in God's eyes regardless of what the government said. I even used it as a teaching moment with my kids to point out that just because it's legal doesn't mean it isn't a sin (like abortion!). And then I became aware of the plank in my own eye - my husband's previous marriage was a joining by God, and a sundering by man. My own marriage was just as invalid as if I was married to a woman. I hesitate to submit my self to an authority (Church) that will surely have difficult remedies for the situation.
I'm still working through this. I understand about forgiveness of sin, and repentance - but how does one repent of an ongoing marriage? I realize I should just make an appointment with a priest and discuss these concerns and get more specific answers than can be provided by a forum - but it's so much more comfortable to be ignorant
Church Authority/Office of the Keys
Covered pretty well in other threads, and I want to say that I'm slowly coming to understand this, but in a very simple fashion. In my understanding Christ called and chose his apostles and sent them out to evangelize - I can look at the New Testament and it is chock full of their instructions and admonitions to the earliest groups of Christians. Somebody has to be in charge of the physical church - and that person, or council, is accountable to God for their leadership. In one of Jesus' parables, a rich man leaves his servants in charge of his talents and then holds them accountable for what they did (and didn't do) with his treasure. I think he'll do the same with our leaders in the church, whether they are Popes, Bishops or pastors. Because the Pope has been entrusted with so much, much will be expected; and much grace will be given as well. It's a formidable job, but sombody has to do it - and it's too important for the Holy Spirit to regard the position and the person filling it with benign neglect.
Apostolic succession is remarkable and inspiring in a very cool way, but I am having a hard time connecting the dots on this as necessary to understand for the sake of salvation? I'm honestly not willfully ignorant, just coming from a decidedly different worldview.
Women Priests (or pastors, as the case may be)
Thankfully that's not my ox in that ditch, I have no quarrel with 1 Tim 2:
Contraception/Artificial Birth Control
I have no issues with this but I am sure it's a stumbling block for many Protestants and some Catholics, too.
I will leave the Justification arguments to others that are better able to articulate them as it seems to me that there is more agreement than disgreement between the Catholic and Lutheran positions.