Since God is merely the generic name for deity, it is better to refer to our deity as Lord. So, I will use the term, Child Of The Lord below.
Not every person is a Child Of The Lord. Because of the fall in Eden the Sin Nature entered into the human spiritual genome separating us from the Lord.
In order for us to be a Child Of The Lord we must be Born Again. Creator God is a Spirit, the Holy Spirit, and so we must become a spirit in order to be His child.
Once a person becomes a spirit being in Christ, they are empowered to manifest as a Son Of God in the same way Christ Jesus did.
But such manifestation requires that the Child Of The Lord is transformed by the Renewing of their mind to the mind of Christ.
When the Child Of The Lord has the Mind Of Christ they are equipped to confront the enemy at any level. The enemy that the Child Of The Lord confronts is in the Hearts and Minds of the lost and the Child Of Satan.
If you are a Child Of The Lord this verse is speaking to you:
Finally, my brethren, be strong in the Lord, and in the power of his might. -
This might of the strength of the Holy Spirit is not just for defense only. It is for offense as well:
And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. -
The Church is the body of Christ. The body of Christ includes everyone who is a Child Of The Lord.
The Gates Of Hell hold captive those who are in bondage to Satan. We are attack those gates with the Sword Of The Spirit - the word of the Lord.
It is the indwelling Holy Spirit that releases the power of the Word in the Child Of The Lord to destroy the "works of the enemy".
Remember, you can do all things through Christ who strengthens you!