We can be a tool for God or Satan. Sincere Christians, true believers, who have laid down their lives to Christ desire to glorify God.  

Peter, a disciple of the Lord Jesus Christ, declared who Jesus was, The Messiah, yet not long after, he was rebuked by Jesus and called satan.  

“…Then Peter took Him aside and began to rebuke Him. But when He had turned around and looked at His disciples, He rebuked Peter, saying, “Get behind Me, Satan! For you are not mindful of the things of God, but the things of men.” Mark 8:32-33

Peter had a heart for Jesus, yet, his mind needed renewing. As a result, he became a tool for satan to use.  

“For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit, the things of the Spirit. For to be carnally minded is death, but to be spiritually minded is life and peace.” Romans 8:5-6

If you desire to be a tool for God, pray for the Lord to show you any wicked way within, “Examine me, O Lord, and prove me; Try my mind and my heart.” Psalm 26:3