'But you have an anointing from the Holy One, and you know all things.' 1 John 2:20
God's Word tells us that we have an anointing from the Holy One, which means God Himself. The Holy Spirit is the Spirit of truth, therefore, believers who have the Spirit of God living inside them, know the deep things of God.
'For what man knows the things of a man except the spirit of the man which is in him? Even so no one knows the things of God except the Spirit of God.' 1 Cor. 2:11
We know things in the spirit because God's Spirit dwell in us.
The anointing simply implies the presence of God and the power of God in and upon our lives.
In the old testament, the kings, the prophets and the priests had the anointing to help them fulfill their call and ministry. In the new testament, all believers are able to receive the Holy Spirit into their lives, if they are open and willing, for God desires to dwell inside us.
Losing the anointing. The anointing of God is linked to our relationship and walk with God. When we sin or disobey God, like King Saul in the old testament and like Judas in the new testament, we will lose the anointing of God as a believer. So, we must walk close with God and in obedience to His Spirit and Word, to allow the anointing to grow in our lives.
God bless you!