I do like the name Jehoshua as that is my favorite to use when using a proper name for the Son of God. However, the dogmatism behind the "proper name" movement misses the very point behind the importance of the name of the Son of God and what it truly means to believe on his name. The name that is important is not Yeshua, Jesus or Jehoshua but it's the name:
"Only begotten Son of God"
That name is the name given to Jehoshua that is more excellent than the angels (Hebrews 1:4-5) as it represents His Davidic Kingship as it comes from Psalm 2:7
"Thou art my Son, this day have I begotten thee"
No angel has the right to sit on the throne of David as Jehovah promised David a royal offspring to establish the Davidic dynasty forever which Jesus fulfilled at his ascension into heaven (Hebrews 1:8-9, Acts 2:29-31, Acts 13:32-36).
In 2nd Samuel 7 Jehovah made a Father-Son covenant relationship with David's royal seed.
This is why it's important to acknowledge that Jehoshua was never an angel as he is fully man of the seed of David.
Philippians 2:9-11
9 Wherefore also God highly exalted him, and gave unto him the name which is above every name;10 that in the name of Jehoshua every knee should bow, of [things] in heaven and [things] on earth and [things] under the earth, 11 and that every tongue should confess that Jehoshua Messiah is King, to the glory of God the Father.
Jehovah God highly exalted Jehoshua at his resurrection and ascension. What is the name Jehovah gave Jehoshua that is above every name? Again, Hebrews 1:4-5 is the answer to that question:
"Thou art my Son, this day have I begotten thee"
This is the name that the angels weren't given at it is a Davidic Kingship title and only the royal offspring of David has a right to that name. John chapter 3 confirms this to be the name that we must believe on to have eternal life:
John 3:16-18
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth on him should not perish, but have eternal life. 17 For God sent not the Son into the world to judge the world; but that the world should be saved through him. 18 He that believeth on him is not judged: he that believeth not hath been judged already, because he hath not believed on the name of the only begotten Son of God.
Notice that John says that those who do not believe in the name of the "only begotten Son" are judged already. John identifies the title "only begotten Son" as the name that we must believe on to have eternal life. This fits with Hebrews 1:4-5 as the name that Jehoshua inherited that was more excellent than the angels.
Back to Philippians, in verse 9 the name given to Jehoshua that is above all names is connected with him being highly exalted by Jehovah God. Hebrews 1:4-5 is in connection with the exhalation of Jehoshua, as that chapter is about the ascension of the Messiah into heaven. Hebrews 1:5 is quoting Psalm 2:7 which is in the context of a coronation of Kingship:
Psalm 2:6-7
6 Yet I have set my king Upon my holy hill of Zion. 7 I will tell of the decree: Jehovah said unto me, Thou art my son; This day have I begotten thee.
If the exhalation of Jehoshua is when he was given the name above all names and that exaltation took place at his ascension, then we have strong evidence that the name above all names is the "only begotten Son", as Hebrews 1:5 is in that context. The passage that Hebrews 1:5 quotes from, Psalm 2:6-7, connects the enthronement of Jehovah's anointed one with the declaration of his begotten Sonship.
Verse 10 of Philippians says that in the name of Jehoshua every knee will bow. Many people use this verse to say it is the actual name of "Jehoshua" that is the name given above all names and while that is true in a sense it doesn't contradict that the name we are to believe on for salvation is the "only begotten Son of God". The title of "only begotten Son" denotes being the Son of inheritance. This is a title rooted in the Davidic covenant (2 Samuel 7:14; Psalm 2:7). A name in the Hebraic mindset denotes character, identity and authority.
Character - Jehoshua is the righteousness of Jehovah God, the spotless lamb.
Identity - Jehoshua is the literal begotten Son of Jehovah God by way the of the virgin birth and by way of the Davidic covenant.
Authority - Jehoshua is the King of Israel and sits on the throne of David having power and authority over heaven and earth.
Verses 10 and 11 of Philippians 2, all in heaven, earth and the grave will bow to Jehoshua and confess that he is Lord (King) to the glory of God the Father. While many use this to say that we have to confess that Jesus is Jehovah because of the title "Lord" that is used here, the use of the word "Lord" should be understood within the context of Psalm 110:1:
"Jehovah saith unto my Lord, Sit thou at my right hand, Until I make thine enemies thy footstool"
Jehoshua is the Lord that is placed at Jehovah's right hand. The word "Lord" here is not the divine name (JHVH) but rather it is "adoni" meaning a human or angelic master. This is also a Davidic covenant fulfillment text as the Lord that is placed at Jehovah's right hand is the prophesied eschatological Davidic King. The Lord of Psalm 110:1 is the royal offspring of David as promised to David in 2 Samuel 7.
1 John 3:23
"And this is his commandment, that we should believe in the name of his Son Jehoshua Messiah, and love one another, even as he gave us commandment"
The first commandment of Jehovah God, after believing that He is the one true God, is to believe in the name of His Son, Jehoshua Messiah. The name that we are to believe in is not simply the name Jehoshua (Jesus), for there are many that have that name but rather it is to believe in the name "only begotten Son of God" because of what that name (title) represents. To say the name that we have to believe on is the name "Jehoshua" leads people into the pronunciation and spelling controversy about how to say the Son of God's name and how to spell it and what name to use. People actually separate over this name controversy on how to say, spell and pronunciate the Son's name.
Again, there are many with the name Jesus (Joshua), so that can't be the literal name we have to believe on. When we understand that name to be "the only begotten Son of God" then we have a true understanding of what it means to believe on Jehoshua's name. Again, the title "only begotten Son" describes the true character, identity and authority of Jehoshua. This title that Jehoshua has separates him from the false versions of Jehoshua taught in Islam, for if we are to take the name literally as "Jehoshua" then it means Muslims have salvation. Obviously that is not the case, so one must believe that Jehoshua is truly the only begotten Son of God to be saved, as this is the biblical Jehoshua.
Martin Luther King, Jr. used the name Jesus in his sermons and speeches but denied his resurrection therefore denying his begotten Kingship. Just because he confesses the literal name of Jesus doesn't mean he believes in the name of Jesus. To believe in the name of Jehoshua one must believe in his literal begotten Sonship and his begotten Kingship:
John 1:49
"Nathanael answered him, Rabbi, thou art the Son of God; thou art King of Israel"
This is the name of Jehoshua we must believe on to have eternal life.