Justin Martyr: Jews Worship the Same God

In his dialogue with Trypho the Jew and his companions, the great saint and martyr Justin Martyr acknowledged that both Jews and Christians worship the same exact God. I cite the relevant section of that discussion. All emphasis will be mine.  

Chapter 10. Trypho blames the Christians for this alone— the non-observance of the law

And when they ceased, I again addressed them.

Justin: Is there any other matter, my friends, in which we are blamed, than this, that we live not after the law, and are not circumcised in the flesh as your forefathers were, and do not observe sabbaths as you do? Are our lives and customs also slandered among you? And I ask this: have you also believed concerning us, that we eat men; and that after the feast, having extinguished the lights, we engage in promiscuous concubinage? Or do you condemn us in this alone, that we adhere to such tenets, and believe in an opinion, untrue, as you think?

Trypho: This is what we are amazed at, but those things about which the multitude speak are not worthy of belief; for they are most repugnant to human nature. Moreover, I am aware that your precepts in the so-called Gospel are so wonderful and so great, that I suspect no one can keep them; for I have carefully read them. But this is what we are most at a loss about: that you, professing to be pious, and supposing yourselves better than others, are not in any particular separated from them, and do not alter your mode of living from the nations, in that you observe no festivals or sabbaths, and do not have the rite of circumcision; and further, resting your hopes on a man that was crucified, you yet expect to obtain some good thing from God, while you do not obey His commandments. Have you not read, that that soul shall be cut off from his people who shall not have been circumcised on the eighth day? And this has been ordained for strangers and for slaves equally. But you, despising this covenant rashly, reject the consequent duties, and attempt to persuade yourselves that you know God, when, however, you perform none of those things which they do who fear God. If, therefore, you can defend yourself on these points, and make it manifest in what way you hope for anything whatsoever, even though you do not observe the law, this we would very gladly hear from you, and we shall make other similar investigations.

Chapter 11. The law abrogated; the New Testament promised and given by God

Justin: There will be no other God, O Trypho, nor was there from eternity any other existing, but He who made and disposed all this universe. Nor do we think that there is one God for us, another for you, but that He alone is God who led your fathers out from Egypt with a strong hand and a high arm. Nor have we trusted in any other (for there is no other), but in Him in whom YOU ALSO TRUSTED, the God of Abraham, and of Isaac, and of Jacob. But we do not trust through Moses or through the law; for then we would do the same as yourselves. But now —for I have read that there shall be a final law, and a covenant, the chiefest of all, which it is now incumbent on all men to observe, as many as are seeking after the inheritance of God. For the law promulgated on Horeb is now old, and belongs to yourselves alone; but this is for all universally. Now, law placed against law has abrogated that which is before it, and a covenant which comes after in like manner has put an end to the previous one; and an eternal and final law — namely, Christ — has been given to us, and the covenant is trustworthy, after which there shall be no law, no commandment, no ordinance. Have you not read this which Isaiah says: ‘Hearken unto Me, hearken unto Me, my people; and, you kings, give ear unto Me: for a law shall go forth from Me, and My judgment shall be for a light to the nations. My righteousness approaches swiftly, and My salvation shall go forth, and nations shall trust in My arm?‘ And by Jeremiah, concerning this same new covenant, He thus speaks: ‘Behold, the days come, says the Lord, that I will make a new covenant with the house of Israel and with the house of Judah; not according to the covenant which I made with their fathers, in the day that I took them by the hand, to bring them out of the land of Egypt‘ (Jeremiah 31:31-32). If, therefore, God proclaimed a new covenant which was to be instituted, and this for a light of the nations, we see and are persuaded that men approach God, leaving their idols and other unrighteousness, through the name of Him who was crucified, Jesus Christ, and abide by their confession even unto death, and maintain piety. Moreover, by the works and by the attendant miracles, it is possible for all to understand that He is the new law, and the new covenant, and the expectation of those who out of every people wait for the good things of God. For the true spiritual Israel, and descendants of Judah, Jacob, Isaac, and Abraham (who in uncircumcision was approved of and blessed by God on account of his faith, and called the father of many nations), are we who have been led to God through this crucified Christ, as shall be demonstrated while we proceed.

Chapter 12. The Jews violate the eternal law, and interpret ill that of Moses

I also adduced another passage in which Isaiah exclaims: Hear My words, and your soul shall live; and I will make an everlasting covenant with you, even the sure mercies of David. Behold, I have given Him for a witness to the people: nations which know not You shall call on You; peoples who know not You shall escape to You, because of your God, the Holy One of Israel; for He has glorified You.

Justin: This same law you have despised, and His new holy covenant you have slighted; and now you neither receive it, nor repent of your evil deeds. For your ears are closed, your eyes are blinded, and the heart is hardened, Jeremiah has cried; yet not even then do you listen. The Lawgiver is present, yet you do not see Him; to the poor the Gospel is preached, the blind see, yet you do not understand. You have now need of a second circumcision, though you glory greatly in the flesh. The new law requires you to keep perpetual sabbath, and you, because you are idle for one day, suppose you are pious, not discerning why this has been commanded you: and if you eat unleavened bread, you say the will of God has been fulfilled. The Lord our God does not take pleasure in such observances: if there is any perjured person or a thief among you, let him cease to be so; if any adulterer, let him repent; then he has kept the sweet and true sabbaths of God. If any one has impure hands, let him wash and be pure.

Chapter 13. Isaiah teaches that sins are forgiven through Christ’s blood

Justin: For Isaiah did not send you to a bath, there to wash away murder and other sins, which not even all the water of the sea were sufficient to purge; but, as might have been expected, this was that saving bath of the olden time which followed those who repented, and who no longer were purified by the blood of goats and of sheep, or by the ashes of an heifer, or by the offerings of fine flour, but by faith through the blood of Christ, and through His death, who died for this very reason, as Isaiah himself said, when he spoke thus:

The Lord shall make bare His holy arm in the eyes of all the nations, and all the nations and the ends of the earth shall see the salvation of God. Depart, depart, depart, go out from thence, and touch no unclean thing; go out of the midst of her, be clean that bear the vessels of the Lord, for you go not with haste. For the Lord shall go before you; and the Lord, the God of Israel, shall gather you together. Behold, my servant shall deal prudently; and He shall be exalted, and be greatly glorified. As many were astonished at You, so Your form and Your glory shall be marred more than men. So shall many nations be astonished at Him, and the kings shall shut their mouths; for that which had not been told them concerning Him shall they see, and that which they had not heard shall they consider. Lord, who has believed our report? And to whom is the arm of the Lord revealed? We have announced Him as a child before Him, as a root in a dry ground. He has no form or comeliness, and when we saw Him He had no form or beauty; but His form is dishonoured, and fails more than the sons of men. He is a man in affliction, and acquainted with bearing sickness, because His face has been turned away; He was despised, and we esteemed Him not. He bears our sins, and is distressed for us; and we esteemed Him to be in toil and in affliction, and in evil treatment. But He was wounded for our transgressions, He was bruised for our iniquities; the chastisement of our peace was upon Him. With His stripes we are healed. All we, like sheep, have gone astray. Every man has turned to his own way; and the Lord laid on Him our iniquities, and by reason of His oppression He opens not His mouth. He was brought as a sheep to the slaughter; and as a lamb before her shearer is dumb, so He opens not His mouth. In His humiliation His judgment was taken away. And who shall declare His generation? For His life is taken from the earth. Because of the transgressions of my people He came unto death. And I will give the wicked for His grave, and the rich for His death, because He committed no iniquity, and deceit was not found in His mouth. And the Lord wills to purify Him from affliction. If he has been given for sin, your soul shall see a long-lived seed. And the Lord wills to take His soul away from trouble, to show Him light, and to form Him in understanding, to justify the righteous One who serves many well. And He shall bear our sins; therefore He shall inherit many, and shall divide the spoil of the strong, because His soul was delivered to death; and He was numbered with the transgressors, and He bore the sins of many, and was delivered for their transgression. Sing, O barren, who bear not; break forth and cry aloud, you who do not travail in pain: for more are the children of the desolate than the children of the married wife. For the Lord said, Enlarge the place of your tent and of your curtains; fix them, spare not, lengthen your cords, and strengthen your stakes; stretch forth to your right and your left; and your seed shall inherit the Gentiles, and you shall make the desolate cities to be inherited. Fear not because you are ashamed, neither be confounded because you have been reproached; for you shall forget everlasting shame, and shall not remember the reproach of your widowhood, because the Lord has made a name for Himself, and He who has redeemed you shall be called through the whole earth the God of Israel. The Lord has called you as a woman forsaken and grieved in spirit, as a woman hated from her youth.’ (Dialogue with Trypho, Chapters 10-30)