What does it mean to pray, ask, or give thanks, "in His Name"?
Our AV translates three different Greek prepositions in the expression "in [someones] name": en (in), (e.g., Matt 12:21), eis (to), (e.g., Matt 10:41), or epí (on), (e.g., Matt 18:5). Six times, the Lord speaks of asking "in My Name" (John 14:13-14; 15:16; 16:23, 24, 26). The seventh association of prayer in the Name of our Lord Jesus Christ is with giving thanks (Eph 5:20). In each of these cases, the preposition is en.
The other 33 times the New Testament uses "en [someones] name" may help us. Mostly, the leading thought is authority. Asking "By what power (dunamis, "dynamic power"), or by [en] what name, have ye done this?" (Acts 4:7), the religious leaders interrogated Peter and John about the healing of the lame man. They questioned what power or authority had effected this miracle. Other passages emphasize the authority and ability of that name, (e.g., Mark 9:38; Luke 10:17; Acts 10:48; 1Cor 5:4; 6:11; James 5:10, 12).
When the Lord spoke of the Spirits coming, "Whom the Father will send in My Name" (John 14:26), He could hardly mean that the Father was acting on His authority. The context in chapters 14-16 teaches that the Father would send the Spirit in His stead, in His interest, and in association with Him (comp 14:26 and 16:7). Similarly, the Lord said, "The works that I do in My Fathers Name, they bear witness of Me" (10:25). The Lord affirmed He was doing "the works of My Father" (v 37) and that they testify "that the Father is in Me, and I in Him" (v 38). The Father was working through the Son (see 5:19) and the Son was working to honor the Father (see 8:54). By working "in My Fathers Name," He worked on His Fathers behalf, in His stead, in His interest, and in association with Him. These passages connote this same thought: Matt 21:9; Mark 9:41; John 5:43; Acts 9:27; Col 3:17; 1Peter 4:14.
Three other passages underline this sense of association with Christ. Commanding the believers in Cornelius house to be baptized "in the Name of the Lord Jesus" was as though the Lord Jesus Himself commanded them (Acts 10:48). As the assembly in Corinth acted in discipline "in the Name of our Lord Jesus Christ," their action was as though the Lord Jesus Himself had acted (1Cor 5:4). The reproach believers suffered "for (en) the Name of Christ" was what their persecutors would have done to Christ Himself (1Peter 4:14).
These New Testament uses suggest that praying in the Name of our Lord Jesus means that we have His authority and enabling to pray to the Father. Praying in His Name means we are asking on His behalf and with His interests in view. We pray in oneness with Him (John 15:7), so that when we pray with His interests in view, the Father regards our requests as being made in His stead. Remarkably then, such prayer in His Name has equal weight with the Father as though the Son Himself made the request!
Is this the same meaning as gathering "in My Name" (Matt 18:20)?
This preposition is eis, which has various shades of meaning. In general, it denotes "entrance into, or direction and limit: into, to, towards, for, among" (Thayer). Newberry therefore suggests "gathered together unto My Name."
Fifteen times the New Testament has the construction "eis [someones] name." Five deal with baptism. Paul asks the Corinthians (1Cor 1:13-15) if they had been baptized into (eis) His Name. This was a response to those who publicly identified themselves with Paul ("I am of Paul"). Those baptized into the Name of the Lord Jesus (Acts 8:16), publicly identified themselves with Him, as did the 12 disciples (19:3-7) who were no longer identified with John and his baptism. The same is true when disciples are baptized into the Name of the Father, and of the Son, and of the Holy Spirit (Matt 28:19). They are no longer linked with the world but with divine Persons. Gathering to the Name of the Lord Jesus, then, publicly links believers to Him in testimony. This is in keeping with the Old Testament truth of the place (Jerusalem) where the Lord placed His Name as a testimony (1Kings 8:41-43).
But the preposition implies "directing (the mind) towards" or "attraction." Receiving prophets or righteous men to (eis) the name of a prophet or righteous man (Matt 10:41; see also v 42) indicates that a person receives a prophet or righteous person because of attraction to what he knows of that person. Hebrew believers work and labor of love was because of their attraction to "the Name" (Heb 6:10).
At least four times John writes of believing "onto" (eis) the Name of Gods Son (John 1:12; 2:23; 3:18; 1John 5:13). Not only does this involve attraction to Him and His claims, but it illustrates the "limit," the place where the motion ends. In trusting Christ for new life, the believer has reached the object he required; he needs nothing more. Furthermore, having reached that limit, he stops; he rests, remains, abides, continues in what he has reached. Christ is sufficient to sustain this new life. We need nothing beyond Him.
Gathering to the Name of the Lord Jesus then means that attraction to Him has brought the believer into identification with Him in testimony. The believer looks for no other name, nothing more than our Lord. He continues (steadfastly!) to enjoy what his Lord is to His people.
When the Lord speaks of being "gathered together unto My Name," He is identified with them and they with Him in their act of discipline (Matt 18:17-20). This clearly is foundational teaching.
What is common to these expressions?
The efficacy of these expressions rests on the peerless value of the Name of our Lord Jesus Christ. We can only know God by the Names by which He has revealed Himself. If "the Name of the Lord is a strong tower: the righteous runneth into it and is safe" (Prov 18:10) and "they that know Thy Name will put their trust in Thee (Psa 9:10), then the more we know of God, the greater our faith and safety.
The Names by which God revealed Himself to Abraham or His people Israel or His disciples in John show how suited He was to their every need! In Him Whose Name is above "every name that is named" (Eph 1:21), what unfathomable treasure is ours! All we are and have and hope to be depends on the unrivaled excellence of Jesus our Lord. All we do or say only has value because of His Name (Col 3:17). "Praise the Name of the Lord" (Psa 113:1)!