Is. 63: 16 is surely clear evidence that Israel knew God as Father, and that the relationship is not unique to the Christian?
The apostle Peter, addressing believing Jews, warns them that “if ye invoke as Father him who, without regard of persons, judges according to the work of each, pass your time of sojourn in fear” (1 Pet. 1: 17). It is remarkable then that when we come to the Psalms—that section of the OT in which, more than any other, the prayers and supplications of godly Israelites are recorded—not once do they invoke God as Father! Leaving aside vague allusions (Ps. 68: 5; 103: 13), the only clear reference to God as Father is in Ps. 89: 26, and that is clearly both prophetic and messianic.
The first place in Scripture where we have the truth of God as Father alluded to is Ex. 4: 22: “Thus saith Jehovah: Israel is my son, my firstborn.” Here we see that the people of Israel as a whole could say of Jehovah, ‘we are his son’, but no single Israelite could say ‘Jehovah is my Father.’ He was only a national Father. Hosea 11: 1 is similar: “When Israel was a child, then I loved him, and out of Egypt I called my son”. Not Israelites, but Israel. What a contrast to Christianity, where the believer knows a personal Father: “nor does any one know the Father, but the Son, and he to whom the Son may be pleased to reveal [him]” (Matt. 11: 27, my emphasis). Thus while Israel of old knew God as Father, it is in a markedly inferior way to what is enjoyed by the Spirit in Christianity.
What of Israel in a future day? In Isaiah 63: 16 we find the Jewish remnant blessing God, and saying “For thou art our Father, though Abraham be ignorant of us, and Israel acknowledge us not: thou, Jehovah, art our Father; our Redeemer, from everlasting, is thy name”, (see also Is. 64: 8). As before, this does not give us God as the Father of the individual Israelite, but only as the Father of Israel. Similarly, Jer. 31: 9, speaking of a future day: “I will be a father to Israel, and Ephraim is my firstborn.” Once again, God is presented as the Father of the nation, not the individual.
Now though there is a vague allusion in Hosea 1: 10 to a future generation of Israelites knowing God individually as Father, it is not really until the ministry of Christ that this is plainly revealed. It is there that we find the thought of God as Father suddenly becoming prominent—it must be so, because the Father was seen in Christ (see John 14: 9). Where in the OT do we read anything like what is detailed in Matt. 6: 6: “But thou, when thou prayest, enter into thy chamber, and having shut thy door, pray to thy Father who is in secret, and thy Father who sees in secret will render [it] to thee” (my emphasis)? Thus, as never before, God is presented as a personal Father. Nor is Matthew 6 speaking about Christianity. The so–called Sermon on the Mount presents the principles of the kingdom, not the Church—and these very Scriptures will be taken up by the Jewish remnant in a coming day. Hence, Israel will then know the Father in a personal way.
However, whilst the teaching recorded in the synoptic Gospels is a significant advance over OT instruction, it still does not present the same level of intimacy that is seen in Christianity. In the synoptic Gospels the Father is often described as a heavenly Father or as in the heavens (see Matt. 6: 14; Mark 11: 25 etc.). All this implies distance—He in heaven, we on earth. It is very significant that after the Lord had died and risen again these terms are never used again. They do not belong to Christianity. Further, the synoptic Gospels present God as Father largely in the sense of the provider of daily need (for example, Matt. 6: 25–34). The Father’s tender care is seen as acting towards believers, but there is no great depth of intimacy—no real communion.
However, consequent on the Lord’s death, resurrection, and ascension, believers can know the Father after the same fashion that Lord knew the Father, (only, as in all things, with Him taking the first place). This is a unique feature of Christianity. Thus the Lord said to Mary: “Touch me not, for I have not yet ascended to my Father; but go to my brethren and say to them, I ascend to my Father and your Father, and [to] my God and your God” (John 20: 17, my emphasis). Until the Lord had ascended into glory, the Spirit could not come (see John 7: 39), but having come, He gives living power to the believer’s relationship with the Father. Thus we read that “for as many as are led by [the] Spirit of God, these are sons of God. For ye have not received a spirit of bondage again for fear, but ye have received a spirit of adoption, whereby we cry, Abba, Father,” (Rom. 8: 14–15). Of course we are “all God’s sons by faith in Jesus”, but it is “because ye are sons” that “God has sent out the Spirit of his Son into our hearts, crying Abba, Father.” (Gal. 3: 26; 4: 6, 7).