Is Jesus Christ of the New Testament the same as Jehovah of the Old Testament?
Yes. The New Testament's Jesus Christ is the Jehovah of the Old Testament and the God of Genesis 1—one and the same God. The only difference is that He manifested Himself in flesh. Saul's encounter confirms this: when he asked who Jehovah was, Jehovah answered, I am Jesus.
Les teaches that people do not understand that Jesus Christ of the New is the Jehovah of the Old, and that Jesus of the New is the God of Genesis 1—one and the same. The only difference is that He manifested Himself in the flesh; it is the same God, the God of glory and creation. Les also points to Saul of Tarsus, who addressed the light and voice as Jehovah and Lord. Jehovah answered, I am Jesus. Saul thought he was doing Jehovah's work by stamping out the name of Jesus, then realized the one he thought was his enemy was in reality the God of Abraham. Les adds that a gentleman once asked him, Who in the world is Jesus Christ? He wished more people would ask that question, because too many do not know.