Colossians 2:2
KJV
That their hearts might be comforted, being knit together in love, and unto all riches of the full assurance of understanding, to the acknowledgement of the mystery of God, and of the Father, and of Christ;
NIV
My goal is that they may be encouraged in heart and united in love, so that they may have the full riches of complete understanding, in order that they may know the mystery of God, [omit] namely, Christ,
Modern versions not only omit the Father, but also define Christ as the mystery of God, which introduces a totally different meaning than the reading of the KJV, where the mystery is of Christ, and of the Father, and of God.
Scripture taken from the Holy Bible, NEW INTERNATIONAL VERSION®, NIV® Copyright © 1973, 1978, 1984, 2011 by Biblica, Inc.® Used by permission. All rights reserved worldwide. NEW INTERNATIONAL VERSION® and NIV® are registered trademarks of Biblica, Inc. Use of either trademark for the offering of goods or services requires the prior written consent of Biblica US, Inc.