Galatians 3:20

and the mediator is not of one, and God is one --

1 Timothy 2:5

for one is God, one also is mediator of God and of men, the man Christ Jesus,

Deuteronomy 6:4

Hear, O Israel, Jehovah our God is one Jehovah;

Hebrews 8:6

and now he hath obtained a more excellent service, how much also of a better covenant is he mediator, which on better promises hath been sanctioned,

Hebrews 9:15

And because of this, of a new covenant he is mediator, that, death having come, for redemption of the transgressions under the first covenant, those called may receive the promise of the age-during inheritance,

Hebrews 12:24

and to a mediator of a new covenant -- Jesus, and to blood of sprinkling, speaking better things than that of Abel!

Genesis 15:18

In that day hath Jehovah made with Abram a covenant, saying, 'To thy seed I have given this land, from the river of Egypt unto the great river, the river Phrat,

Genesis 17:1-2

And Abram is a son of ninety and nine years, and Jehovah appeareth unto Abram, and saith unto him, 'I am God Almighty, walk habitually before Me, and be thou perfect;

Job 9:33

If there were between us an umpire, He doth place his hand on us both.

Acts 12:20

And Herod was highly displeased with the Tyrians and Sidonians, and with one accord they came unto him, and having made a friend of Blastus, who is over the bed-chambers of the king, they were asking peace, because of their country being nourished from the king's;

Romans 3:29-30

The God of Jews only is He, and not also of nations?

Galatians 3:17

and this I say, A covenant confirmed before by God to Christ, the law, that came four hundred and thirty years after, doth not set aside, to make void the promise,

Treasury of Scripture Knowledge

Summary

Now a mediator is not a mediator of one, but God is one.

Bible References

A mediator is

Job 9:33
If there were between us an umpire, He doth place his hand on us both.
Acts 12:20
And Herod was highly displeased with the Tyrians and Sidonians, and with one accord they came unto him, and having made a friend of Blastus, who is over the bed-chambers of the king, they were asking peace, because of their country being nourished from the king's;
1 Timothy 2:5
for one is God, one also is mediator of God and of men, the man Christ Jesus,

But

Galatians 3:17
and this I say, A covenant confirmed before by God to Christ, the law, that came four hundred and thirty years after, doth not set aside, to make void the promise,
Genesis 15:18
In that day hath Jehovah made with Abram a covenant, saying, 'To thy seed I have given this land, from the river of Egypt unto the great river, the river Phrat,
Genesis 17:1
And Abram is a son of ninety and nine years, and Jehovah appeareth unto Abram, and saith unto him, 'I am God Almighty, walk habitually before Me, and be thou perfect;
Deuteronomy 6:4
Hear, O Israel, Jehovah our God is one Jehovah;
Romans 3:29
The God of Jews only is He, and not also of nations?

General references

Deuteronomy 5:3
not with our fathers hath Jehovah made this covenant, but with us; we -- these -- here to-day -- all of us alive.
Romans 3:30
yes, also of nations; since one is God who shall declare righteous the circumcision by faith, and the uncircumcision through the faith.
James 2:19
thou -- thou dost believe that God is one; thou dost well, and the demons believe, and they shudder!