Forgiveness  of sin is only achieved when there is  the shedding of blood (Hebrews 9:22). Blood in question is not that of animals because the bloods of animals could only purify the flesh but it cannot purify the soul and the Spirit  (Hebrews  9:13). Only the blood of Jesus has the power to purify the soul and the spirit  (Hebrews 9:14).

It was only after Jesus shed His blood that the sin of man could be forgiven by God. Adam came physically to the earth before Jesus, hence Jesus had not died or shed His blood while Adam was on earth ad sinned. As a result, Adam's sins could not be forgiven by God.

Also, Adam's sins could not be atoned for because there was no provision for animal sacrifice in the garden which, could have been used for atonement of his sins.

We need the Holy Spirit in every area of our lives as believers, as He functions to help us live the christian life.

The Holy Spirit bears witness of Jesus Christ. (1Jhn 5:8, Jhn 15:26).

He bears witness with the spirit of the believer (Rom 8:16) that we are children of God.

He acts as a our teacher and reveals the will of God to us (Jhn 14:26).  

He helps to produce godly character in the life of a believer in a way that we cannot do of our own (Phil 2:12-13). 

He empowers believers to carryout ministerial duties (Acts 1:8, Matt 28:19-20).        

The Holy Spirit can be insulted when the grace of God is misused by speaking evil of Him, act shamefully towards Him, and behave wantonly and insolently to Him.(Hebrews 10:29)

The Holy Spirit is not a value neither a force but, a person in the God head and equal to the Father & the Son in every way (Matt 28:18-20). So, the Holy Spirit proceeds from the Father & the Son.

1. The Bible tells us that lying to the Holy Spirit is lying to God (Acts 5:3-5).
2. He is omnipresent as God. (Ps 139:7-8). 
3. He is omniscience as God. (1cor 2:10-11 ). 
4. He is omnipotent as God. (Lk 1:35.)

To be filled with the Holy Spirit is to allow the Holy Spirit do all He has come to do in your life. As believers, we are only able to allow the Holy Spirit work in us by meditating on the word of God, Praying in the language of the Holy Spirit, avoid living in or enjoying sin. Also, it requires that we do not conduct our life in the energy of the flesh (Prov.3:5), by resisting God and relying on ourselves. When a believer is filled with the Holy Spirit He yields himself to be forever led by the Holy Spirit. (Rom 8:14-17)

To destroy the works of the devil and to fulfill the requirements of the law. 1 John 3:8

God wanted man to be involved with the relationship He had with them. So it was to give a sense of togetherness & responsibility. Exo 25:8.

The principles of the Christian faith are thus;

1. Repentance from dead works,
2. Faith toward God,
3. Doctrine of baptism,
4. Laying on of hands,
5. Resurrection of the dead&  
6. Eternal judgement. (Heb 6:1-2)