Jesus of Nazareth is "Emmanuel", "God with us", per Apostle Matthew in Matthew 1:23. Matthew was pointing to the Isaiah 7 prophecy that Christ would be born of a virgin with His name as "Immanuel" ("Emmanuel" is the Greek version).
Per Apostle John in John 4:24, "God is a Spirit". John was pointing to the Heavenly dimension, the world of Spirit. If one does not understand about the two separate dimensions of existence per God's Word, this 'earthly' one vs. the 'heavenly' one, then they will struggle to understand these things.
Study of all The Bible helps clear this matter up.
Per God's Word, we were created with 3 parts, a spirit, a soul, and bones and marrow (Hebrews 4:12). Ecclesiastes 12:5-7 revealed that when our flesh body dies, it goes back to the earthly elements where it came from, but our 'spirit' goes back to GOD Who gave it. Per Matt.10:28 Jesus revealed that no man can kill our soul, so that has to mean our soul and spirit are tied together separate from our flesh body.
Eccl.12 reveals a thing Solomon called the "silver cord" which keeps our spirit/soul attached to our flesh body while alive in this earthly dimension. When that "silver cord" is severed at flesh death though, that is when our flesh goes back to the earth where it came from, and our spirit/soul goes back to God, meaning in the heavenly dimension. Per 2 Corinthians 5, Apostle Paul showed that if our earthly house (flesh) were dissolved, we still have another body, not made with hands (meaning non-flesh), from God, eternal in the heavens (meaning the spiritual body which is of that Heavenly dimension.)
How then does the above help us understand about Christ's birth in the flesh, and His previous existence as GOD The Son? The idea of The Triune Godhead is a mystery, but the way God's Word describes it is that The Father, and The Son, and The Holy Spirit, are all Co-Equal as GOD. This is why Jesus would say to Philip that those who had seen Him have seen The Father (John 14:9). It is because Hebrews 1 reveals that Jesus is the "express image of His Person", meaning the express image of The Father.
This means we CANNOT separate Jesus of Nazareth from His Spirit inside Him as GOD, even while He was in the flesh. But this is something the orthodox unbelieving Jews are constantly trying to do, confusing many Christian brethren that are unlearned in these things.
Jesus took on flesh like us to suffer for us on His cross, to offer those who believe on Him remission of sins through His death and resurrection. In this The Christ was different in Office than The Father.
It is also interesting that when you research the name Jesus back to the Greek, and then to the Hebrew, it cannot be separated from The Father's Name. When you say Jesus Christ, you are automatically including The Father, and when you say The Father's Name, you are automatically including The Son Jesus Christ.