First, your assumption that I am a Catholic is incorrect. I just believe what the Bible says, and it says the Christ is the seed of Abraham, and we in Christ are the inheritors of that Covenant. Read ALL of Galatians - its really very short. Paul is very clear on this point. I can see no other way to understand the fulfillment of the Old Covenant in the New Covenant. In the first chapter of Galatians Paul says that this did not come to him from man, but by revelation. And this revelation puts all the parts in place - in really is a beautiful picture!
Not if you don't believe God's promise to bring the nation of Israel back to their land and turn them to Him.
>>and it says the Christ is the seed of Abraham,<<
But not the seed of Isaac.
>>and we in Christ are the inheritors of that Covenant.<<
Not the covenants made with Israel.Supersessionism is NOT from scripture.