Process theology is the philosophical and theological position that God is changing as is the universe. Therefore, our knowledge of God must be progressing as we learn more about Him, and it can never rest in any absolutes, which is why process theologians deny the absolutes of God's immutability and truth. Furthermore, this would mean that absolute knowledge of God would not be achievable and a self-revelation of God (in the person of Jesus Christ and the Bible) would also not be possible. This would open the door for humanistic philosophy and/or false theological systems to be "rationalized" by process theologians.
Logically speaking, if process theology maintains that God is progressing and changing, then given an infinite amount of time in the past, God may not have actually been God. Also, it could be argued from this perspective that there is something outside of God that works upon Him, bringing Him into a greater knowledge and increased greatness. This would be problematic because it would need to study what that "something" is.
In process theology, God does not know the future exhaustively. He can guess at what may or may not happen, but absolute knowledge is not attainable until events actually occur.
Process theologians deny that Jesus Christ is God in flesh, and, therefore, mankind has no need for salvation.
Process theology denies the Scriptures which teach that God has always been God (Psalm 90:2) and that God is unchanging (Malachi 3:6, Hebrews 13:8). Of course, it denies and contradicts God's Word regarding the necessity of the Savior and the deity of Christ (John 1:1, 14, Colossians 2:9).