Another Way to Look at "I will never forsake you."

...for He Himself has said,
"I will never desert you,

nor will I ever forsake you."

Hebrews 13:5b

NASB

This verse, and its parallels in Deuteronomy 31 and Joshua 1, is most visibly demonstrated in the incarnation.  God came to earth as man, Immanuel--God with us, God among us, God sharing our condition, God fully identifying with us in our humanity and its lowliness, our humanity and its loneliness, our humanity and its sorrows, our humanity and its temptations, our humanity and its limitations, our humanity and its weaknesses, our humanity and its sadness, our humanity and its pains, our humanity and its desires, our humanity and its death.  

In the incarnation, God deliberately and purposefully became one with us.  And if He intentionally became so identified with us, why would He ever leave us?  One of the benefits of the incarnation is that it is a ground of our assurance before God.