HolySpiritSeal

In whom you also trusted, after that you heard the word of truth, the gospel of your salvation: in whom also after that you believed, you were sealed with that Holy Spirit of promise, -

When we heard the Gospel of Truth we believed it, received it and trusted it.
In so doing we signed the New Covenant that the Holy Spirit offered to us by the preaching of the Word.
As a result, we were Born Again and made New Spirit beings In Christ Jesus.

Our New Spirit is perfect.
Our sanctification in the New Birth made us eligible to receive the Holy Spirit.

So, every such Born Again believer who asks for the baptism of the Holy Spirit is filled with Him.

This baptism of the Holy Spirit is the seal of the New Covenant, He was promised and His presence in us holds promise of power going out of us.

And grieve not the Holy Spirit, whereby you are sealed unto the day of redemption. -
We grieve the Holy Spirit when we operate contrary to the Lord. He is the Lord in us. We must learn to let Him use our body for His purpose.

Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our Lord in their foreheads. -
The Lord never punishes the just with the unjust. We are justified by faith in Christ Jesus.

And it was commanded them that they should not hurt the grass of the earth, neither any green thing, neither any tree; but only those men which have not the seal of the Lord in their foreheads. -
So, there are believers, sealed withe the Seal Of God, still on the earth at the time of the fifth trumpet.

Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and you shall receive the gift of the Holy Spirit. -
So, repentance is necessary for the remission of sins after which it is expected that the believer receive the gift of the Holy Spirit.

If you then, being evil, know how to give good gifts unto your children: how much more shall your heavenly Father give the Holy Spirit to them that ask him? -
The Lord is so much more loving and giving than the best of parents.     He will give the Holy Spirit to anyone who asks Him.
The reality is that many believers do not want to manifest as Sons Of The Holy Spirit.     They are content to just miss hell and enter heaven when they die.
But without the baptism of the Holy Spirit believers are ineffective as witnessed by the decline of the church and the secularization of society.
Jesus commanded the disciples to tarry in jerusalem until they received the power of the Holy Spirit.     Only then were they to go forth preaching the Gospel of the kingdom.
If the disciples who walked with Jesus needed Spirit Baptism, on what basis do believers think that they do not?

To whom the Holy Spirit would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory: -
The Holy Spirit, by virtue of Christ Jesus, has imparted Himself into believers and thereby brought them into His glory as His sons.
We have the same Spirit in us that raised Christ Jesus from the dead.
All things are possible to him that believes.

So we see that
→ the Holy Spirit is the Spirit Of Christ Jesus,
→ that He is given to those who receive the Gospel and ask for Him to abide in them,
→ that He is our seal of acceptance,
→ that His presence in us is to manifest His glory in and through us.