I’m not sure what you mean about Christ’s two wills, so I’ll respond to the first question.
Council of Constantinople III declared that Christ has two wills (one Divine and one human).
Remember first of all that while we believe that the Bible is the highest authority, no protestant would hold that it is the only source of truth.
I highly doubt that “no Protestant would hold that it is the only source of truth.” Protestants can’t even agree on what Sola Scriptura even means.
If I’m going to fix my car or have heart surgery, I’m relying upon truth learned outside of Scripture.
I’m referring to truth with regards to the Christian Faith.
The Bible does not contain all the truth that is to be known, but is the highest authority in what it addresses, so if evolution and the Bible contradict, we follow the Bible.
Let me give you the Catholic side. As Catholics, we believe the Bible is the WRITTEN Word of God; however, we don’t believe that everything was written down. We believe some things were passed down orally as well (2 Thess 2:15, 1 Thess 2:13). The things that were passed down orally are ALSO the Word of God. So now we have two things:
1.) The written Word of God (Bible)
2.) The oral Word of God (Tradition)
If one says “the Bible (written) Word of God is the highest authority” then what one is saying is “the written Word of God is more authoritative than the oral Word of God.” In other words, the Word of God is more authoritative than the Word of God. That makes absolutely no sense. There isn’t one higher than the other. They complement each other and help us understand what each source is saying. Without Tradition, the Bible is hard to interpret accurately (and I would say impossible). Likewise, without the Bible, Tradition would be hard to interpret accurately.
Since we have two sources that we believe to be the Word of God (and Scripture recognizes them as the Word of God in 2 Thess 2:15 and 1 Thess 2:13) then we now need an interpreter to these sources. Not merely human interpreter, but one that is inspired by the Holy Spirit. This is what we call the Magesterium. This is where the councils are held and where the Bishops have authority due to their Apostolic Succession. These councils, we believe, are inspired by the Holy Spirit (Acts 15, Matthew 18) and we believe that there is one who has primacy over all (Matthew 16).
With all that said, please understand that when someone says something like “We regard other sources to be useful but the Bible is the most useful and the Bible is the most authoritative” then here is where the problem lies:
IF these other sources have things that are not found in the Bible, are they still binding on all Christians? For example, Christ having two wills is no where to be found in the Bible. This is something a council proclaimed in the late 7th century. Is this something that you believe? If so, where can I find “Christ having two wills” in the Bible? It’s no where to be found. Also, Canon of Scripture is also no where to be found in the Bible. So I must go outside the Bible in order to know more truths that are necessary for my salvation (such as the canon of Scripture).
Having said that, because the church recognized the canon, does not mean that it created the canon.
The Holy Spirit “created” the Canon and inspired the Church to proclaim this canon. The Holy Spirit is at work in the councils and that is why they cannot err (the Ecumenical ones).
Is it not possible for me to come to the same conclusion as the council?
Sure it’s possible. Is it also not possible that you would come up with a different conclusion as the council? How would we know who is right? You recognize the council of Nicea in 325 AD because it proclaims the Trinity, right? But have you read every single thing in that canon? There are things on there that you may not agree with. So what you have done is, you have made yourself the final authority and you are now above the councils. Do you see the problem with “coming up with the same conclusion on your own”? The councils are inspired by the Holy Spirit and they cannot err. They are binding on Christians because (just like the Bible) it is the Holy Spirit that inspired the councils and men (bishops) who are the instruments. People tend to forget that this is the way the Holy Spirit usually works.
1.) Bible: Penned by men, inspired by the HS.
2.) Jesus: 100% man and 100% God
3.) Councils: Held by men (Bishops) and inspired by the HS
4.) Traditions: Spoken by Jesus (God) and continued by men (Bishops).
God is not going to rely on our fallible minds to come up with a doctrine. He started a Church so that He can communicate His truth to the successors of the Apostles so that us laymen can know the truth at all times without coming up with educated guesses. See Matthew 16 and Matthew 18. Also see:
“But if I should be delayed, you should know how to behave in the household of God,
which is the church of the living God, the pillar and foundation of truth.”
-1 Timothy 3:15.
The early Church Fathers recognized the Church as a visible establishment as well as an invisible one. They all agree that in order to be in the actual Church, one must be obedient to the Bishop. Some even went as far as saying that in order to be in the actual Church, one must be in communion with the Bishop of Rome. I’d be more than happy to provide you these references if you’d like.