How does the Holy Spirit assure believers that they are children of God?
The Holy Spirit bears witness with the believer's spirit that they are children of God, providing inward assurance of salvation. This witness assures believers they have passed from death unto life, replacing bondage and fear with confidence in God's love, and confirming they are led by the Spirit as God's born ones.
Les explains that if we are led by the Spirit of God, then we are the sons, or the born ones, of God—one of the proofs of the pudding. The believer has not received the spirit of bondage again to fear; believers do not have to walk around in constant fear, though they revere God, because they know He loves them. Les illustrates from John chapter 13, where Jesus dealt with Martha, Mary, and Lazarus, that it was not how much Lazarus and Mary loved Jesus, but how much He loved them. He says this is what people have to realize: salvation is not dependent on how much we love Him, although we will love Him, but on realizing how much He loved us, enough to die for us and suffer for us. When we have that kind of salvation, the Holy Spirit bears witness with our spirit that we are the children of God. Les notes this flies in the face of those who say you can never really know; the Bible makes it plain that we can know we have passed from death unto life, and it is the witness of the Holy Spirit that we have that salvation.
The Spirit itself beareth witness with our spirit, that we are the children of God:
More Questions
How do we know we are children of God?
When we have that kind of salvation, the Holy Spirit bears witness with our spirit that we are the children of God.
Does the Holy Spirit reveal that we are God's children now or only in the future?
The Holy Spirit (better called 'Himself' than 'itself') bears witness with our spirit that we are already—present tense, not future—children of God.
Are believers children of God right now or only in the future?
The Holy Spirit Himself bears witness with our spirit that we are already, in the present tense, children of God, not merely ones who will be children in the future.