Why does Romans 10:9 say confession must be made with the mouth? Is that a requirement for salvation?

Why does Romans 10:9 say confession must be made with the mouth?  Is that a requirement for salvation?

Romans 10:9:  "That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved."

Brian Kelson's answer:  In Romans verse 1 & 21, Israel remain God's people and Paul's desire is their salvation.

Rom 10:1  Brethren, my heart's desire and prayer to God for Israel is, that they might be saved.

Rom 10:2  For I bear them record that they have a zeal of God, but not according to knowledge.

Rom 10:21  But to Israel he saith, All day long I have stretched forth my hands unto a disobedient and gainsaying people.

In verse 4, Christ is the object or goal of the Law as per Gals.3, and thus the Law witnessed to the righteousness in Him as per Roms.3:20-22 (Roms.10:12). So we have this link between Israel fixated upon the Law and the testimony of the Law against their zeal and lack of faith which Moses speaks against in verse 5;

Rom 10:5  For Moses describeth the righteousness which is of the law, That the man which doeth those things shall live by them.

Then Paul quotes Moses as per the righteousness of faith in verses 6-8 thus;

Rom 10:6  But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:)
Rom 10:7  Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.)
Rom 10:8  But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;

Notice Moses spoke of the heart and mouth in verse 8, and Paul flows on from this with the same words in verse 9-10 and thus the salvation by faith through grace is all in the OT

Rom 10:9  That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
Rom 10:10  For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.

What is important is that Paul is constantly quoting the Old testament Scriptures which clearly speak of the salvation in view at that time, that is during Acts. There is no such instruction to confess with the mouth in the post Acts epistles. Also, confession was essential for the restoration of those sick because of their trespasses as in James 5. During Acts there were spirits who needed to be tested, 1Jn.4:1 and in 1Cor.12:3 only those empowered by the Spirit could say Jesus is Lord. Romans is an Acts period epistle and is understood in that dispensation.

Now, back to Romans 10 where the OT quotes continue to pour out of the apostle;

Rom 10:10  For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.

Rom 10:11  For the scripture saith, Whosoever believeth on him shall not be ashamed.

Rom 10:12  For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him.
Rom 10:13  For whosoever shall call upon the name of the Lord shall be saved.

Roms.10:11 is a quote from Is.28 which he had already used back in 9:33 and where the faith Paul is writing about is linked with Zion which appears directly and indirectly in Romans many times. Here is Is. used by Paul in 10:11Isa 28:16  Therefore thus saith the Lord GOD, Behold, I lay in Zion for a foundation a stone, a tried stone, a precious corner stone, a sure foundation: he that believeth shall not make haste.

Do we see how practically the entire chapter 10 of Romans is Old Testament. Look at these verses;Rom 10:10  For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
Rom 10:11  For the scripture saith, Whosoever believeth on him shall not be ashamed.
Rom 10:12  For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him. See Ps.86:5, 145:18, Is.55:6, Paul had used Is.55 back in Acts 13:34
Rom 10:13  For whosoever shall call upon the name of the Lord shall be saved.

Romans 10:13 is a direct quote from Joel thus;Joe 2:32  And it shall come to pass, that whosoever shall call on the name of the LORD shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the LORD hath said, and in the remnant whom the LORD shall call.

Once again Mount Zion and all those who call upon the name of the Lord shall be delivered which is precisely what Paul says in chapter 11:25-27.

So what gospel is it in chapter 10? Paul tells us in verse 15 which is a quote from good old Isaiah yet again (I hope we don't see Zion again because then it would be rather impossible to insert heavenly places as the hope of Romans); 

Rom 10:15  And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!

Isa 52:7  How beautiful upon the mountains are the feet of him that bringeth good tidings, that publisheth peace; that bringeth good tidings of good, that publisheth salvation; that saith unto Zion, Thy God reigneth!

Isa 52:8  Thy watchmen shall lift up the voice; with the voice together shall they sing: for they shall see eye to eye, when the LORD shall bring again Zion.

Isa 52:9  Break forth into joy, sing together, ye waste places of Jerusalem: for the LORD hath comforted his people, he hath redeemed Jerusalem.

Isa 52:10  The LORD hath made bare his holy arm in the eyes of all the nations; and all the ends of the earth shall see the salvation of our God.

Isa 52:11  Depart ye, depart ye, go ye out from thence, touch no unclean thing; go ye out of the midst of her; be ye clean, that bear the vessels of the LORD. (cp 2Cor.6:17).

So Israel have not all obeyed the gospel found in the Old Testament. And even that is as per Isaiah again;

Rom 10:16  But they have not all obeyed the gospel. For Esaias saith, Lord, who hath believed our report?

Isa 53:1  Who hath believed our report? and to whom is the arm of the LORD revealed?

Is.53 is all about the rejected Messiah who was made an offering for sin and who would justify many and is a prophesy about Israel, not the church which is His Body. When will mid-Acts accept that Paul's gospel in Romans is Old Testament based and he meant what he said in Acts 26:22. But let us finish the chapter.

Having quoted the OT so many times this is what Paul concludes;
Rom 10:17  So then faith cometh by hearing, and hearing by the word of God.

Faith comes be hearing WHAT word? The Word of the Mystery hidden in God? Impossible in this context. Paul goes on to peel things out of the OT; 

Rom 10:18  But I say, Have they not heard? Yes verily, their sound went into all the earth, and their words unto the ends of the world.

Psa 19:4  Their line is gone out through all the earth, and their words to the end of the world. In them hath he set a tabernacle for the sun,

Psa 19:5  Which is as a bridegroom coming out of his chamber, and rejoiceth as a strong man to run a race.

Psa 19:6  His going forth is from the end of the heaven, and his circuit unto the ends of it: and there is nothing hid from the heat thereof.

Psa 19:7  The law of the LORD is perfect, converting the soul: the testimony of the LORD is sure, making wise the simple.

Psa 19:8  The statutes of the LORD are right, rejoicing the heart: the commandment of the LORD is pure, enlightening the eyes.

Psa 19:9  The fear of the LORD is clean, enduring for ever: the judgments of the LORD are true and righteous altogether.

Psa 19:10  More to be desired are they than gold, yea, than much fine gold: sweeter also than honey and the honeycomb.

Psa 19:11  Moreover by them is thy servant warned: and in keeping of them there is great reward.

Don't we love the reference to the Law and the Bridegroom in the Psalm? So consistent with the Acts period.

Romans 10:19-21 are direct quotes from the OT.

Roms.10:19 = Deut.32:21 (see verse 35-36 & 43 and compare Roms.12:19 [Hebs.10:30], Roms.15:10.

Roms.10:20-21 = Is.65:1-2 where Israel were stubborn but the Gentile inclusion is all prophetic.

Those who find a problem in the confession with the mouth which may, by the grace of God lead them into a mountain of problems in the same chapter when Romans is taught by mid-Acts as the dispensation of the grace of God.

My own summary: 

That scripture always bothered me because it seemed to add something to the gospel. Now I understand that it's connected to the scriptures of the OT prophets and is according to Israel's prophecy:

Deuteronomy 30:14 But the word is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it.

That scripture is the basis for:
Romans 10:8 But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;

Joel 2:32 And it shall come to pass, that whosoever shall call on the name of the LORD shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the LORD hath said, and in the remnant whom the LORD shall call.

This is the basis for:
Romans 10:13 For whosoever shall call upon the name of the Lord shall be saved.

Salvation for the Israelite (and Gentiles who looked to be included in the kingdom on earth) was the kingdom itself, not a going to heaven hope like we have. They looked for Mount Zion and Jerusalem to be physically delivered from their enemies and for the messiah to rule.

That's why I believe now that during the Acts period, of which Romans was the last Pauline letter written before Israel was temporarily set aside, Paul was offering the kingdom and preaching the new gospel of grace that was part of the New Covenant God was offering Israel.

We're saved by the same gospel of grace but without all this kingdom prophecy stuff added in to embellish and authenticate it to his hearers. And our doctrine is found in Ephesians, Colossians, Philippians, Titus, Philemon, Timothy. There are only about 6 or 7 OT scriptures found in all these letters, while there are 70 in Romans alone!

There's a reason Paul's earlier epistles sound so Jewish and that's why.