No more than it was Jesus' God, who believed
the OT was the "word of God" in every detail (Mt 15:6, Lk 5:1, Lk 11:28, Jn 10:35),
that it was the truth of God vested with the authority of God and backed by the power of God (Mt 5:17-19).
He treated arguments from Scripture as having clinching force. When he said, "It is written," that was final. There was no appeal against Scripture, for "the scripture cannot be broken." (Mt 4:5, Mt 4:7, Mt 4:10, Jn 10:35). God's word holds good forever.
He constantly scolded the Jews for their ignorance and neglect of Scripture: "Are you not in error because you do not know the Scriptures?". . ."Have you not read. . .?". . .Go and learn what this means. . ." (Mk 12:24, Mt 12:3, Mt 12:5, Mt 19:4, Mt 21:16, Mt 21:42,
Mt 9:13).
Likewise, Jesus himself submitted to the OT as the word of God:
he lived a life of obedience to Scripture (Lk 4:17-21, Mt 8:16-17, Mt 11:2-5),
and then he died in obedience to Scripture (Lk 18:31, Mk 8:31, Mk 9:31, Mk 10:33-34, Mt 26:24, Lk 22:37, Mt 26:53-56),
when he arose, he explained who he was by the Scriptures (Lk 24:44-47, Lk 24:27),
he presented himself to the Jews as the fulfiller of Scripture (Jn 5:39-40, Jn 5:46-47).
Belief in the authority and truth of the OT was the foundation of Jesus' whole ministry.
However, my faith is not based on reason.
My faith is based on the testimony of the Holy Spirit to my spirit that Scripture is the truth of God, whether it seems "reasonable" or not.
Jesus paying the debt of my guilt is not based on reasonableness, but on faith.