Yahweh

 When we see in many of our translations God referred to as LORD all in capital letters, the Hebrew word there is "Yahweh".  My concordance translates that as "He who is" and in Vine's Expository Dictionary, part of the description is "God who exists".  This is the self-existent, uncreated, infinite, eternal God.

That's the "LORD" referred to in Psalm 23:1; Yahweh is the one who is my shepherd.  He leads me and guides me, protects me and provides for me.  He even has me eating feasts in the very presence of my enemies.  Because He is always with me, even in the valley of the shadow of death, "I will fear no evil."  My future is secure as "surely (no doubt about it) (His) goodness and mercy follow me all the days of my life" and in the "forever", I will dwell right in His house. 

Jesus proclaimed Himself as the "I Am" a good number of times in the gospels.  We have His seven "I am" statements in John:  "I am the bread of life" (6:35), "I am the light of the world" (8:12), "I am the door of the sheep" (10:7), "I am the good shepherd" (10:11),  "I am the resurrection and the life" (11:25), "I am the way, the truth, and the life" (14:6), "I am the true vine...I am the vine" (15:1, 5).  That is a pretty comprehensive list describing who He is.

My husband once worked with a Muslim who tried to claim that Jesus never claimed to be the Son of God.  Jesus not only repeatedly called God His Father, but by calling Himself the "I Am", He referred to Himself as God.  One instance where He had the Pharisees incensed because He used the "I AM" as an indication that He was God, and they considered it blasphemy is recorded in John 8:56 (Jesus is speaking to the Jews):  "'Your father Abraham rejoiced to see My day, and he saw it and was glad.'  Then the Jews said to Him, 'You are not yet fifty years old, and have You seen Abraham?'  Jesus said to them, 'Most assuredly, I say to you, before Abraham was, I AM.'  Then they took up stones to throw at Him, but Jesus hid Himself and went out of the temple, going through the midst of them, and so passed by."

We find a similar assertion when the soldiers came to arrest Him in the garden of Gethsemane with Judas as their guide.  When Jesus asked, "Whom are you seeking?"  they answered, "Jesus of Nazareth."  Jesus' reply as recorded in most of our English translations is, "I am He".  Some translations have the "He" (or "he") in italics, indicating that that word is not in the original Greek.  A few translations like the International Standard version, the Literal Standard version, and the New American Bible simply translated it directly as "I am" (John 18:5).  This statement was so full of power that the whole crowd "drew back and fell to the ground."  Again, Jesus was declaring that He was God.

Knowing that we have our Yahweh always with us, that Jesus our LORD resides in us by His Spirit, is enough to give us rest and confidence no matter what we face.  Yahweh is our good shepherd.