The Apostle Paul asked this of the Corinthian church in order to show them that they had no right to think they were better than another. If they were anything, it was because of God. The Father had given them everything they possessed, and made them anything good that they had become. He was the only one who could receive the glory.
The same truth applies to each of us. None of us is, or has anything that was not given to us by God. Our Salvation was a gift. So was the faith to receive it. The Holy Spirit living within us, who causes us to be born again and separated for God...He too is a gift. This truth will change our lives when it's applied to our practical, everyday walk with the Lord.
Everything He desires from us can be summed up in one line spoken by Jesus:
"There is only one thing important". (Luke 10:42) The "One Thing" can be simply defined as "Absolute Surrender to Him". If the church was absolutely surrendered to knowing God and obeying Him, it would be enjoying so much more of the power and blessings we know are available.
But surrender seems so hard. Sometimes we are afraid to surrender all, or we feel inadequate to even say it, as we sit in prayer, trembling from fears or shamed by sin. But that is where the great truth comes in. It's not in
your power to do it! Everything we are has been given to us. We didn't earn it, deserve it, or achieve it. It was a gift. This applies to total surrender. The Lord requires nothing from us, except what He first gives us. He will give us
His ability to accomplish it. It begins by knowing He demands it, then simply saying from our heart, "Lord I surrender it all to You - every person, possession, and position. Have Your way in my life". The prayer may seem weak and feeble at first, but if you say it from your heart, the Father will take over and begin to guide and bless your life like you have always known He desires to do.
"
For it is God who is at work in you, both to will
and to work for His good pleasure." (Phil.2:13) 
