For as many as are led by the Spirit of God, these are sons of God. (Romans 8:14 NKJV)
We are sons of God, if we are led by the Spirit of God. God has given us His Spirit to abide in us as born-again children of God. We are to live a life led by the Spirit. The Spirit helps us as our teacher, guide and counselor.
The Spirit Himself [thus] testifies together with our own spirit, [assuring us] that we are children of God. (Romans 8:16 AMPC)
The Holy Spirit in us bears a witness or testifies to our own spirits. God speaks to us in our spirits, by the inner voice or the witness of the Holy Spirit within.
And you have forgotten the exhortation which speaks to you as to sons:“My son, do not despise the chastening of the Lord, Nor be discouraged when you are rebuked by Him; For whom the Lord loves He chastens, And scourges every son whom He receives.” If you endure chastening, God deals with you as with sons; for what son is there whom a father does not chasten? But if you are without chastening, of which all have become partakers, then you are illegitimate and not sons. Furthermore, we have had human fathers who corrected us, and we paid them respect. Shall we not much more readily be in subjection to the Father of spirits and live? For they indeed for a few days chastened us as seemed best to them, but He for our profit, that we may be partakers of His holiness. Now no chastening seems to be joyful for the present, but painful; nevertheless, afterward it yields the peaceable fruit of righteousness to those who have been trained by it. (Hebrews 12:5-11 NKJV)
God as our Father disciplines us. The children who do not receive the discipline and the direction are illegitimate sons. In order words, they are not led by the Spirit, but by the flesh. These carnal, flesh-led Christians are illegitimate sons. They don’t acknowledge the Lordship of Jesus Christ in their lives and decisions.
According to Psalm 127:1, “Unless the Lord build the house, they labor in vain that build it.” Notice that the still labor and build a house, but it’s a house built on flesh which will not be according to the plans and purposes (blue-prints) of God. They are not led by the Spirit in building their house.
2 Timothy 3:16-17 tells us that Scripture is profitable for instruction, reproof and correction. Therefore, two thirds of the purpose of the Word of God is for correction and conviction. God disciplines us by His Word.
2 Timothy 4:2-4 tells us that preaching of the Word is to reprove, rebuke and exhort. Two thirds of preaching is reproving and rebuking, but there those who only want to hear exhortation. They look for people who will only tell them words that will make them feel comfortable. They don’t want to be challenged. The Word will challenge us. The Holy Spirit only works with and confirms the Word. The Holy Spirit will never ever confirm a lie, or false doctrine. All things must be tested according to the Word of God. All spirits must be tested. (1 John 1-6).