How to reconcile 1 John 4:15 with Mathew 8:29?

Question

The fourth chapter of 1 John talks about how we should test every spirit, for not every spirit is of God, because many false prophets have gone out into the world. It says in verse 15:

1 John 4:15 (KJV): Whosoever shall confess that Jesus is the Son of God, God dwelleth in him, and he in God.

How should I understand that when I read Mathew 8:29 the demons, when they see Jesus walking towards them, they shout:

What have we to do with you, Jesus, you Son of God? have you come here to torment us before the time? (KJV)

Answer 1

The semantics of "confess" can differ. When John (1 John 4:2) and Paul (Romans 10:9) are saying it, it is with a simultaneous notion of participation and reciprocation from the side of a confessor in and with the salvational Action of the Word of God.

Thus, this confession means embracing and co-acting with this Action, in order to grow in Christ, for otherwise, with sluggishness and slackening of efforts the very confession will avail for nothing not only for demons but also for a hypocrite men. Do we not read that there are those who gladly receive the word of salvation, but do not cultivate it and make it wither through worldly concerns (Mark 4:16)? Thus, "to believe in heart that God raised Jesus", means that the heart should be in a condition of willingness to fulfil Christ's commandments, because for any Christian Jesus' physical resurrection from death should become not an outward fact of history, but an intrinsic part of their own life and inner experience (Gal. 2:20), and moreover, his/her own physical resurrection at the end of the times, should be necessarily prefigured and preconditioned by "resurrection" from sinfulness to righteous life in Christ already in his/her historical life (cf. Roman 6:4). Without this disposition of free response and willingness of human heart and conscience the confession by lips is good for nothing: it cannot automatically save anybody, like a magical incantation. Salvation does not apply to those who praise Lord by lips, while their hearts are far from Him (Isaiah 29:13).

Therefore, demons are not really confessing in this sense in Matthew 8:29, but simply acknowledging the fact of Jesus' divinity, without any will to repent before Him, their Creator, whom they are afraid of to the point of trembling (James 2:19), but do not obey in freedom and love.

Answer 2

The epistle of I John states that it is possible to identify those who are "not of God". A key to understanding this is found in John chapter 8, where Jesus expanded on this, as he spoke to those who opposed his ministry.

Jesus said unto them, If God were your Father, ye would love me: for I proceeded forth and came from God; neither came I of myself, but he sent me. He that is of God heareth God's words: ye therefore hear them not, because ye are not of God. John 8:42,47

Jesus explained that those that are "of God" are those that hear God's words, and come to know and love Jesus Christ. In the process, he identified those who were "not of God" to everyone with ears to hear. These men were "antichrist" (as mentioned in I John 4) because they were in opposition to Christ.

In a record in Matthew chapter 8, Jesus cast out some evil spirits that correctly identified him as the son of God.

And, behold, they cried out, saying, What have we to do with thee, Jesus, thou Son of God? art thou come hither to torment us before the time? Matthew 8:29

Although devil spirits sometimes (try to) pass themselves off as good spirits, they are also identified as "not of God" by their opposition to Jesus Christ.

Spirit beings who are "of God", angels, are sent forth to minister, and are "teammates" with God, Jesus Christ, and believers.

And it came to pass ...two men stood by them in shining garments: And ...said unto them, Why seek ye the living among the dead? He is not here, but is risen... Luke 24:4-6

As we grow in our understanding of I John, we enhance our fellowship with God and other believers.

That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ. I John 1:3

Answer 3

The explanation is straight forward. The demons acknowledge Jesus as "son of god." They do not confess He is "The Son of God:"

And behold, they cried out, “What have you to do with us, O Son of God?... (Matthew 8:29) [ESV]

καὶ ἰδοὺ ἔκραξαν λέγοντες τί ἡμῖν καὶ σοί υἱὲ τοῦ θεοῦ ἦλθες ὧδε πρὸ καιροῦ βασανίσαι ἡμᾶς

Whoever confesses that Jesus is the Son of God, God abides in him, and he in God.
(1 John 4:15)

ὃς ἐὰν ὁμολογήσῃ ὅτι Ἰησοῦς ἐστιν ὁ υἱὸς τοῦ θεοῦ ὁ θεὸς ἐν αὐτῷ μένει καὶ αὐτὸς ἐν τῷ θεῷ

Anyone born of a woman of Jewish ancestry, who was a son of Abraham (Matthew 1:1) could make the claim God was their father, and, therefore, be called a son of God:

³⁹ They answered him, “Abraham is our father.” Jesus said to them, “If you were Abraham's children, you would be doing the works Abraham did, ⁴⁰ but now you seek to kill me, a man who has told you the truth that I heard from God. This is not what Abraham did. ⁴¹ You are doing the works your father did.” They said to him, “We were not born of sexual immorality. We have one Father—even God.” (John 8)

Calling one of Jewish ancestry a son of God, as the demons do, essentially is an Old Testament presumption. That is to say, the demons could have called Peter, James, John, or any of those of Jewish ancestry traveling with Jesus, "σοί υἱὲ τοῦ θεοῦ" (you son of God). However, John states you must confess Jesus is the Son of God. He is not "Jewish" although He is of Jewish ancestry; He is the only-begotten Son of God. This the demons did not do.

Jesus went on to say their "father" was the devil, not God:

You are of your father the devil, and your will is to do your father's desires. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies. (John 8:44)

Therefore, the demons, like those whom Jesus is addressing in John 8, are of their "father," the devil; they are not of God.