You can believe in someone you do not personally know through testimony about that person, through evidence, etc., but the nature of that belief is entirely different from the belief you have in someone you do personally know. In the first case the belief was really all coming from yourself. In the second case it is the other person who convinces you to believe in them. Only if it is actually God who convinces you to believe in him will your belief be unchanging. What is critical is that God does not make himself known to us in a solely private way. He makes himself known to us each personally only in the way that he makes himself known to the world. And more than this, he does not make himself known to the world in the way that the world chooses, or that any of us personally chooses, but only in the way that he has, himself, chosen to make himself known to the world. And this is as the God of Israel. Unless we come to know him personally as the God of Israel, in the way he makes himself known to the world, we cannot truly come to know him personally.
God himself created Israel. Know one can define Israel but God. No one can say that Israel is this or is that, is not this or is not that, exists or does not exist now or will exist or will not exist in the future. God created Israel and defined Israel by his word, by promise and covenant with Abraham, Isaac and Jacob and then by redeeming Israel out of Egypt and giving Israel his Torah. God created Israel and immediately began to redeem Israel, and this is how he reveals himself to the world and the way He will be known. For all eternity he will be known as the Eternal Redeemer and God of Israel. It is his purpose that his promised Anointed One, the Messiah, should make him known in all the world in this way.
God’s Anointed One is called Christ, as translated from Greek. As translated from Hebrew, he is called Messiah or Mashiach. You cannot believe in him except in accordance with the Scriptures. To begin with, this means in accordance with God’s redemption of Israel from Egypt. It is in that redemption that he was promised as “the Lamb of God which takes away the sin of the world”. If you name the name of Christ, or the name of Messiah, or Mashiach, and do not know this, the strength of your faith and your service to God will greatly increase if you come to understand this well.
That redemption was how the Creator first revealed Himself and to be also a Redeemer. You can believe in him in your way, but if you do not believe in this way, as the Redeemer of Israel, you will need to give an account for the difference between your faith and the faith God himself stated he was seeking to produce in him, when he redeemed Israel.
7 And He said to him, "I am the Lord, Who brought you forth from Ur of the Chaldees, to give you this land to inherit it." זוַיֹּ֖אמֶר אֵלָ֑יו אֲנִ֣י יְהֹוָ֗ה אֲשֶׁ֤ר הֽוֹצֵאתִ֨יךָ֙ מֵא֣וּר כַּשְׂדִּ֔ים לָ֧תֶת לְךָ֛ אֶת־הָאָ֥רֶץ הַזֹּ֖את לְרִשְׁתָּֽהּ:
8 And he said, "O Lord God, how will I know that I will inherit it?" חוַיֹּאמַ֑ר אֲדֹנָ֣י יֱהֹוִ֔ה בַּמָּ֥ה אֵדַ֖ע כִּ֥י אִֽירָשֶֽׁנָּה:
9 And He said to him, "Take for Me three heifers and three goats and three rams, and a turtle dove and a young bird." טוַיֹּ֣אמֶר אֵלָ֗יו קְחָ֥ה לִי֙ עֶגְלָ֣ה מְשֻׁלֶּ֔שֶׁת וְעֵ֥ז מְשֻׁלֶּ֖שֶׁת וְאַ֣יִל מְשֻׁלָּ֑שׁ וְתֹ֖ר וְגוֹזָֽל:
10 And he took for Him all these, and he divided them in the middle, and he placed each part opposite its mate, but he did not divide the birds. יוַיִּקַּח־ל֣וֹ אֶת־כָּל־אֵ֗לֶּה וַיְבַתֵּ֤ר אֹתָם֙ בַּתָּ֔וֶךְ וַיִּתֵּ֥ן אִֽישׁ־בִּתְר֖וֹ לִקְרַ֣את רֵעֵ֑הוּ וְאֶת־הַצִּפֹּ֖ר לֹ֥א בָתָֽר:
11 And the birds of prey descended upon the carcasses, and Abram drove them away. יאוַיֵּ֥רֶד הָעַ֖יִט עַל־הַפְּגָרִ֑ים וַיַּשֵּׁ֥ב אֹתָ֖ם אַבְרָֽם:
12 Now the sun was ready to set, and a deep sleep fell upon Abram, and behold, a fright, a great darkness was falling upon him. יבוַיְהִ֤י הַשֶּׁ֨מֶשׁ֙ לָב֔וֹא וְתַרְדֵּמָ֖ה נָֽפְלָ֣ה עַל־אַבְרָ֑ם וְהִנֵּ֥ה אֵימָ֛ה חֲשֵׁכָ֥ה גְדֹלָ֖ה נֹפֶ֥לֶת עָלָֽיו:
13 And He said to Abram, "You shall surely know that your seed will be strangers in a land that is not theirs, and they will enslave them and oppress them, for four hundred years. יגוַיֹּ֣אמֶר לְאַבְרָ֗ם יָדֹ֨עַ תֵּדַ֜ע כִּי־גֵ֣ר | יִֽהְיֶ֣ה זַרְעֲךָ֗ בְּאֶ֨רֶץ֙ לֹ֣א לָהֶ֔ם וַֽעֲבָד֖וּם וְעִנּ֣וּ אֹתָ֑ם אַרְבַּ֥ע מֵא֖וֹת שָׁנָֽה:
14 And also the nation that they will serve will I judge, and afterwards they will go forth with great possessions. ידוְגַ֧ם אֶת־הַגּ֛וֹי אֲשֶׁ֥ר יַֽעֲבֹ֖דוּ דָּ֣ן אָנֹ֑כִי וְאַֽחֲרֵי־כֵ֥ן יֵֽצְא֖וּ בִּרְכֻ֥שׁ גָּדֽוֹל:
15 But you will come to your forefathers in peace; you will be buried in a good old age. טווְאַתָּ֛ה תָּב֥וֹא אֶל־אֲבֹתֶ֖יךָ בְּשָׁל֑וֹם תִּקָּבֵ֖ר בְּשֵׂיבָ֥ה טוֹבָֽה:
16 And the fourth generation will return here, for the iniquity of the Amorites will not be complete until then." טזוְד֥וֹר רְבִיעִ֖י יָשׁ֣וּבוּ הֵ֑נָּה כִּ֧י לֹֽא־שָׁלֵ֛ם עֲוֹ֥ן הָֽאֱמֹרִ֖י עַד־הֵֽנָּה:
17 Now it came to pass that the sun had set, and it was dark, and behold, a smoking furnace and a fire brand, which passed between these parts. יזוַיְהִ֤י הַשֶּׁ֨מֶשׁ֙ בָּ֔אָה וַֽעֲלָטָ֖ה הָיָ֑ה וְהִנֵּ֨ה תַנּ֤וּר עָשָׁן֙ וְלַפִּ֣יד אֵ֔שׁ אֲשֶׁ֣ר עָבַ֔ר בֵּ֖ין הַגְּזָרִ֥ים הָאֵֽלֶּה:
18 On that day, the Lord formed a covenant with Abram, saying, "To your seed I have given this land, from the river of Egypt until the great river, the Euphrates river. יחבַּיּ֣וֹם הַה֗וּא כָּרַ֧ת יְהֹוָ֛ה אֶת־אַבְרָ֖ם בְּרִ֣ית לֵאמֹ֑ר לְזַרְעֲךָ֗ נָתַ֨תִּי֙ אֶת־הָאָ֣רֶץ הַזֹּ֔את מִנְּהַ֣ר מִצְרַ֔יִם עַד־הַנָּהָ֥ר הַגָּדֹ֖ל נְהַר־פְּרָֽת:
19 The Kenites, the Kenizzites, and the Kadmonites, יטאֶת־הַקֵּינִי֙ וְאֶת־הַקְּנִזִּ֔י וְאֵ֖ת הַקַּדְמֹנִֽי:
20 And the Hittites and the Perizzites and the Rephaim, כוְאֶת־הַֽחִתִּ֥י וְאֶת־הַפְּרִזִּ֖י וְאֶת־הָֽרְפָאִֽים:
21 And the Amorites and the Canaanites and the Girgashites and the Jebusites." כאוְאֶת־הָֽאֱמֹרִי֙ וְאֶת־הַכְּנַֽעֲנִ֔י וְאֶת־הַגִּרְגָּשִׁ֖י וְאֶת־הַיְבוּסִֽי: