Show me where Bible mentions the word "Christianity"

All languages have words derived from root words

You cannot derive a word from root word. Confusing deduction with adding.

Christianity existed before it was called that. The Bible existed before it was called the Bible.

Says who? You? Your credentials, pls. I have them and have cited them. You?

Not really.

Christianity was largely a European power base that developed a strategy based upon a previous creation and existence hypothesis of Judean folk tales and myths, that was developed into a book called the Bible.

Islam was a competing power base and emulated the Christian strategy, referring to it as Islam with it's own associated book and prophet.

Says who? You? Your credentials, pls. I have them and have cited them. You?

Deduction means deducing from something, not adding to.

The term "Christianity" is not mentioned in the Bible, but the word "Christian" appears three times in the New Testament: 

Acts 11:26, Acts 26:28, and 1 Peter 4:16. These verses describe the first followers of Jesus being called "Christians" by outsiders in Antioch, with the term likely being used derisively at first. 

1. Acts 11:26: States that "the disciples were called Christians first in Antioch".
2. Acts 26:28: King Herod Agrippa II says to Paul, "Almost thou persuadest me to be a Christian".
3. 1 Peter 4:16: Exhorts believers to "if any man suffer as a Christian, let him not be ashamed". 

Even that is terribly unclear, doesnt say to call yourself Christian. Its a nickname given by others.

The word "Christianity" 

comes from "Christian," a term first used in the city of Antioch to describe followers of Jesus, meaning "follower of Christ". The term likely originated with outsiders and was first recorded in the New Testament book of Acts 11:26, but the earliest known use of "Christianity" (Χριστιανισμός) itself was around 100 AD by Ignatius of Antioch. 

Origin of the term "Christian"

1. Location: The name was first applied to Jesus's disciples in the city of Antioch.
2. Etymology: "Christian" is derived from the Greek name for Christ, Χριστός (Christos). The Latin word is Christianus, which means "a follower of Christ".
3. Purpose: The suffix "-ianos" was common in Roman society for people who followed a particular leader, so "Christian" meant "one belonging to the Christ".
4. First use: The term appears in the New Testament, most notably in Acts 11:26, where it states, "...the disciples were called Christians first in Antioch". 

Origin of the word "Christianity"

1. First recorded use: The term Christianity(Χριστιανισμός) was first recorded by Ignatius of Antioch, who was an early church leader, around 100 AD.
2. Foundation: The word is built upon the term "Christian" and refers to the religion that developed from the life and teachings of Jesus. 

Bible doesnt say "Call yourself Christian and tell religion is Christianity".

The Bible doesn't explicitly say "Call yourself Christian and tell religion is Christianity,"

 but it does say that followers of Jesus were first called "Christians" in Antioch, as recorded in the book of Acts 11:26. While the Bible describes a way of life centered on Christ, some believe "Christianity" as an organized religion is a human construct, whereas others see it as a valid term for the faith and its relationship with God.