Paul was encouraging the Christians to have the same humility as Jesus had… That same chapter Paul says
9Therefore God also highly exalted him
and gave him the name
that is above every name,
10 so that at the name of Jesus
every knee should bend,
in heaven and on earth and under the earth,
11 and every tongue should confess
that Jesus Christ is Lord,
to the glory of God the Father.
Definition of exalted means to raise in rank, power, or character. Can ask yourself again, If Jesus was equal to God why did God have to exalt him not only on earth but also in heaven… Does it not make you wonder
The “exalting” of Jesus is a reference not to his being equal to God, but being exalted from the state he had as a human.
6 Though he was in the form of God,
he did not consider being equal with God something to exploit.
7 But he emptied himself
by taking the form of a slave
and by becoming like human beings.
When he found himself in the form of a human,
8 he humbled himself by becoming obedient to the point of death,
even death on a cross.
9 Therefore, God highly honored him
and gave him a name above all names,
10 so that at the name of Jesus everyone
in heaven, on earth, and under the earth might bow
11 and every tongue confess that
Jesus Christ is Lord, to the glory of God the Father.
Notice that the Scripture is speaking about Christ’s “exaltation” or how “God highly honored him” due to his humbling suffering at the Cross. It isn’t saying that God made him a different entity of higher existence but bestowing honor.
As the text clearly states, Christ’s pre-human state did not prevent him from humbling himself to suffer and die as a human. However you wish to translate it, the Scripture here states that Christ had the choice between equality with God or humility as a suffering human. The text said he grasped the latter.
But who else besides God can make such a choice? No one but God Almighty can truly choose between being equal to God (or ‘exploiting this equality,’ as this more modern translation puts it) or humbling himself to something lesser. No angel, archangel, not even Satan comes anywhere close to what God is. The only one who can exploit or choose between grasping equality with God or humanity is God as being equal to God is only accessible to God.
And this has to be a literal equality within the grasp of Christ, because if it is not then why write that Christ was honored or exalted for the choice he made between the two?