In the book of Isaiah, God calls Himself redeemer more than 5 times.
Do you know the word that means "redeemer" there? It is ga' al. Do
you know what it means? Consider the following use of the same word...

Leviticus 25:25 "If thy brother be waxen poor, and hath sold away some
of his possession, and if any of his kin come to redeem it, then shall
he redeem that which his brother sold."

or

Leviticus 25:48-50 "After that he is sold he may be redeemed again;
one of his brethren may redeem him: Either his uncle, or his uncle's
son, may redeem him, or any that is nigh of kin unto him of his family
may redeem him; or if he be able, he may redeem himself. And he shall
reckon with him that bought him from the year that he was sold to him
unto the year of jubile: and the price of his sale shall be according
unto the number of years, according to the time of an hired servant
shall it be with him."

or

Numbers 5:7-8 "Then they shall confess their sin which they have done:
and he shall recompense his trespass with the principal thereof, and
add unto it the fifth part thereof, and give it unto him against whom
he hath trespassed. But if the man have no kinsman to recompense the
trespass unto, let the trespass be recompensed unto the LORD, even to
the priest; beside the ram of the atonement, whereby an atonement shall
be made for him."

In each case, the word redeem is the same as the Name by which the Lord
called Himself. It means to pay the debt of another. Therefore, God
would have to pay our debts HIMSELF in order to be called Redeemer, and
He would be a liar to call Himself that without the payment. God
cannot lie. Therefore God must pay our debts, which He did in Jesus
Christ.

However, if Jesus Christ was not God, Himself, then Jesus, not God,
would be the Redeemer. Therefore, God wouldn't be just to take credit
for Jesus death and wouldn't be the Redeemer. If Israel was the
redeemer (as they currently view themselves) for the rest of the world,
then Israel would be the redeemer, not God. Again, God would be a liar
to call Himself the redeemer. The only way this Name of God is Just is
if Jesus Christ is God and died for our sins. Otherwise, God is a liar
and is not just to condemn anyone.