Well then for what purpose are you asking whether you NEED to keep them? So that you will be accepted by God or so you will feel good about yourself?
***Am I still required to "keep the sabbath holy"?***
The new requirements meet and exceed the old requirements. Every part of the Christian's life is the be holy. Our very bodies are a sacrifice to Him.
Romans 12:1
I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.
Do you think you can keep the other six days unholy?
But by what power are we to do this, seeing that we were unable to keep even the lesser requirement of the Law? By the power of the new birth, regeneration, the indwelling Spirit. We are not "required" to do anything because all we can do is fail. When we, by faith, accept God's free gift of salvation He gives us gives us a new heart that wants to keep the law and He gives us the Holy Spirit which is the power to keep the Law. This is the promise of the new covenant.
"For this is the covenant that I will make with the house of Israel after those days, declares the Lord:
I will put my laws into their minds,
and write them on their hearts,
and I will be their God,
and they shall be my people."
As Paul said...
"For God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness of sinful flesh and for sin, he condemned sin in the flesh, in order that the righteous requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit." - Rom 8
The basis of our acceptance before God is the blood of Christ alone - nothing more, nothing less. The person who, by faith, has entered into this covenant of grace will desire to do, by virtue of their new nature, anything and everything that pleases God. These acts are done out of gratitude and love, not out of a desire to rack up points in the hope of earning God's acceptance.
***Which "Gospels?" Paul's epistles predate the writing of all the gospels. I think you mean "Scriptures" which would have been what we know as the Old Testament only.***
Actually Paul in 1 Tim. quotes Luke, (or a variant of Matt.) and calls it "Scripture". Theories about the precise date of compilation of the Gospels are only theories. Paul quotes the words of Christ as "Scripture". Many people are suprised to learn this.
*** As a nation has civil authority, so to does the Apostolic Church have a spiritual authority.***
Well if you are under the law then you have fallen from grace...
Galatians 5:4
"Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace."
***The Church does not come from the Bible, the Bible comes from the Church***
This is not strictly true. "Scripture" as a source of final authority existed long before the Church in the form of the OT. Scripture predates the Church.
Scripture is the Word of God. It is God's voice to us put down in black and white. It is ultimatley not the product of man but the breath of God Himself.
Mary may have given birth to Jesus but that didn't make her Jesus' master did it? Even so the Church may have given birth to the New Testament but that doesn't mean it is master over the New Testament.
***The Bible, albeit an integral part of a Christian person's faith cannot be their foundation ***
You are correct, the Bible without obedience is no foundation. But Jesus promised us...
"Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock."
That sounds like a pretty firm foundation to me.
*** in every denomination there is an infallible interpreter of God's eternal Word: either the successor to Peter as appointed by Christ or yourself.***
Who interprets "Peter's successor" (i.e. the Magesterium) to YOU? You must read the voluminous history of interpretation put out by the Magesterium in order to understand it, but how do you know you've interpreted the Magesterium's teaching correctly???
If you think you are incapable of understanding the Bible then WHY do you thing you are capable of understanding the Magesterium?