Ro 8:16 – The Spirit itself beareth witness with our spirit, that we are the children of God:
MHCC
Ro 8:17 – v10-17 If the Spirit be in us, Christ is in us. He dwells in the heart by faith. Grace in the soul is its new nature; the soul is alive to God, and has begun its holy happiness which shall endure for ever. The righteousness of Christ imputed, secures the soul, the better part, from death. From hence we see how much it is our duty to walk, not after the flesh, but after the Spirit. If any habitually live according to corrupt lustings, they will certainly perish in their sins, whatever they profess. And what can a worldly life present, worthy for a moment to be put against this noble prize of our high calling? Let us then, by the Spirit, endeavour more and more to mortify the flesh. Regeneration by the Holy Spirit brings a new and Divine life to the soul, though in a feeble state. And the sons of God have the Spirit to work in them the disposition of children; they have not the spirit of bondage, which the Old Testament church was under, through the darkness of that dispensation. The Spirit of adoption was not then plentifully poured out. Also it refers to that spirit of bondage, under which many saints were at their conversion. Many speak peace to themselves, to whom God does not speak peace. But those who are sanctified, have God’s Spirit witnessing with their spirits, in and by his speaking peace to the soul. Though we may now seem to be losers for Christ, we shall not, we cannot, be losers by him in the end.
FBN
Ro 8:16 – The Spirit itself; the Holy Spirit. Beareth witness with our spirit; by working in us the dispositions, and leading us to form the habits and cherish the hopes of the children of God; and by his influence, enabling us to discern in ourselves these scriptural evidences of being born of God.
PNTC
Ro 8:16 – The Spirit himself beareth witness with our spirit, that we are the children of God. The Spirit of God is one witness to the fact. Our spirit is a corroborative witness. How do each bear witness? (1) Witness is usually borne in words, but not always. God’s Spirit bears witness in words (see Heb 10:15). The Holy Spirit shows us how we must become God’s children, and how to continue the Christian life. (2) It bears testimony in our lives by its fruits [Mt 7:16]. Do we bear the fruit of the Spirit? (See Ga 5:22-23). (3) Does our own spirit testify that we “mind the things of the Spirit?” [Ro 8:5]. Does our consciousness recognize its fruits, inward as well as outward? If the testimony of our spirit is that what God’s Spirit witnesseth of the sons of God is true of us, then they concur in the testimony that we are the children of God.
Witness
The witness here is “Summartureo” which is to mean to bear witness with, bear joint witness.
In whole KJV, this word was only used four times! also bear witness 2, testify unto 1, bear witness with 1.
Rev 2:18 18 For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book:
Romans 2:15 Which shew the work of the law written in their hearts, their conscience also bearing witness , and their thoughts the mean while accusing or else excusing one another
Romans 8:16 The Spirit itself beareth witness with our spirit, that we are the children of God:
Romans 9:11 I say the truth in Christ, I lie not, my conscience also bearing me witness in the Holy Ghost,
My personal thoughts
What is my witness with the Holy Spirit that i am in Christ? I use the verse of faith resulting in works as an outward evidence and witness of internal working of the Holy Spirit. Jas 2:20 But wilt thou know, O vain man, that faith without works is dead?
There must be
1. Change life
2. Change of direction towards God
3. There must be attributes of the Holy Spirit Gal 5:22
But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, Meekness, temperance: against such there is no law.
4. Abhor the flesh
Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness, Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies,Envyings, murders, drunkenness, revellings, and such like
5. Desire and consuming spiritual food
6. Desire and persistent relationship with God. Prayer. Meditation.
7. Shifting of priorities towards God.