The NIV translates the word μορφῇ in Philippians 2:6 as ‘nature’:
5 In your relationships with one another, have the same mindset as Christ Jesus:
6 Who, being in very nature[a] God,
Philippians 2:5-8 NIV
did not consider equality with God something to be used to his own advantage;
7 rather, he made himself nothing
by taking the very nature[b] of a servant,
being made in human likeness.
8 And being found in appearance as a man,
he humbled himself
by becoming obedient to death—
even death on a cross!
However, this is not a good translation of the word μορφῇ. In Mark 16:12 in the NIV the very same word μορφῇ is translated as ‘form.’ It is very clear from the context of Mark 16;12 that the word means ‘form’ and not ‘nature’:
12 Afterward Jesus appeared in a different form to two of them while they were walking in the country.
Mark 16:12 NIV
Therefore, we see that Philippians 2:6 should actually be translated as: ‘Who being in very form God’. Verses 7 and 8 reinforce the fact that Jesus was the ‘form’ of God before He became Jesus by discussing His human ‘form’ and human appearance as opposed to His human character or personality. Verse 7 say Jesus was made in ‘human likeness’ i.e. he took human form and verse 8 says that he was found in appearance as a man i.e. he looked like a man. Clearly before this He had the visible form or appearance of God.
Numbers 12:7;8 says:
Not so with My servant Moses. He is faithful in all My house. I speak with him face to Face and even plainly and not in dark sayings and he sees the form of Yahweh….
Numbers 12:7;8 Interlinear
We know from the Old Testament that God appeared as Yahweh Sabaoth and as the Angel of Yahweh when humans could see Him. It seems to me that Jesus was both Yahweh Sabaoth and the Angel of Yahweh and that Yahweh Sabaoth is the Angel of Yahweh.
However, Yahweh told Moses in Exodus 33:23 that His face must not be seen.
23 Then I will remove my hand and you will see my back; but my face must not be seen.”
Exodus 33:23 NIV
And in verse 20 He told Moses that no one can see His Face and live:
20 But,” he said, “you cannot see my face, for no one may see me and live.”
Exodus 33:20 NIV
The only explanation that I can think of for this apparent contradiction is that when Yahweh usually appeared to Moses, He appeared in the form of a man. However, in Exodus 33 He decided to appear to Moses in the form of the Angel that He truly was. This is why Moses could only look at His back. Clearly, when Isaiah saw Yahweh Sabaoth in Isaiah 6, He also saw Him in the appearance of a Man in the same way that Moses had seen Him as a Man or else he would not have survived the experience of seeing God.