Protestant objections to Catholic Teaching

Lutero said:

How else can Rome justify her theological novelties, such as auricular confession, universal jurisdiction of the bishop of Rome, and the Marian dogmas of the Immaculate Conception and the Assumption? How can Rome legislate regulations such as celibacy and feasts of obligation without Biblical warrant unless it suppresses the ultimate authority of the Word of God?

Response:

How else can Rome justify her theological novelties, 

It is Protestantism which produces theological novelties.

such as auricular confession, 

It is because Protestants have rejected Tradition that they can't recognize the Sacraments in Scripture.  Auricular confession to a priest is strongly implied in the following verses:

John 20:23
King James Version (KJV)
²³ Whose soever sins ye remit, they are remitted unto them; and whose soever sins ye retain, they are retained.

This, of course, also happens with Baptism.  Where the sins of those who are Baptized are washed away.  But it also implies the power to forgive sins in the Sacrament of Confession.  Especially when the following verses are considered:

Hebrews 13:17
King James Version (KJV)
¹⁷ Obey them that have the rule over you, and submit yourselves: for they watch for your souls, as they that must give account, that they may do it with joy, and not with grief: for that is unprofitable for you.

This is striking.  Note that it is in the Confessional that the Priest accounts for our souls.  And it is in the Confessional where we most frequently, directly submit to and must obey the Priest.  This verse specially describes auricular confession.  But it also includes within its parameters, all the other Sacraments.

2 Corinthians 5:17-19
King James Version (KJV)
¹⁷ Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.¹⁸ And all things are of God, who hath reconciled us to himself by Jesus Christ, and hath given to us the ministry of reconciliation;¹⁹ To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation.

Another name for the Sacrament of Confession is the Sacrament of Reconciliation.  Remember that we live after 2000 years of Magisterial refinement of theological terminology.   The term "ministry of reconciliation" could very easily be the very same thing as "Sacrament of Reconciliation".  Based upon this verse and the other two and many more, it certainly can't be ruled out and must be considered a very strongly implied.  

universal jurisdiction of the bishop of Rome, 

Jesus committed His Flock to one of the Apostles:

John 21:17
King James Version (KJV)
¹⁷ He saith unto him the third time, Simon, son of Jonas, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee. Jesus saith unto him, Feed my sheep.

He named that Apostle "Rock" or "Peter", a name previously reserved for God.  And  then He gave that same Apostle the keys to the Kingdom:

Matthew 16:18-19
King James Version (KJV)
¹⁸ And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.¹⁹ And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.

That sounds like universal jurisdiction to me. 

and the Marian dogmas 

All of them are strongly implied in Scripture.  Certainly, none of them blatantly contradict the Scriptures as do the Protestant doctrines like Sola Scriptura (2 Thess 2:15) and Sola Fide (James 2:24).

of the Immaculate Conception 

In Scripture, God calls Mary "kecharitomene" or "full of grace" through His Angel:

St. Luke 1 (Douay Rheims):
[26] And in the sixth month, the angel Gabriel was sent from God into a city of Galilee, called Nazareth,[27] To a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin's name was Mary. [28] And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women. [Luke 1:28] [Latin] [29] Who having heard, was troubled at his saying, and thought with herself what manner of salutation this should be. [30] And the angel said to her: Fear not, Mary, for thou hast found grace with God.

and the Assumption?

St. John saw the Virgin Mary in heaven, body and soul:

Revelation 12:1
King James Version (KJV)
1 And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars:

How can Rome legislate regulations 

Jesus Christ gave the Church authority:

Matthew 28:18-20
King James Version (KJV)
¹⁸ And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth.¹⁹ Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:²⁰ Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.

And commanded that all men should obey the Church:

Matthew 18:17
King James Version (KJV)
¹⁷ And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.

such as celibacy 

The Church obeys the Word of God:

1 Corinthians 7:32
King James Version (KJV)
³² But I would have you without carefulness. He that is unmarried careth for the things that belong to the Lord, how he may please the Lord:

and feasts of obligation

Hebrews 10:25-31
King James Version (KJV)
²⁵ Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching.  ²⁶ For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,  ²⁷ But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.  ²⁸ He that despised Moses' law died without mercy under two or three witnesses:  ²⁹ Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace  ³⁰ For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people.  ³¹ It is a fearful thing to fall into the hands of the living God.

without Biblical warrant 

It is commanded in Scripture.  But you simply don't recognize it because you have rejected the Traditions.

 unless it suppresses the ultimate authority of the Word of God?

It is Protestants which have suppressed the authority of the Word of God in Tradition and Scripture, casting aside the Will of God to follow their traditions of men.

Sincerely,

De Maria