For Ignorant Non-Christians

The most common thing non-christians will use to attack Christianity is the Trinity. They tell Christians that they are polytheists and that they don't know God. They also say that is is impossible for God to be three. They interperate the Trinity as three different gods whithout even searching for the Trinity in Christian doctrine.

God is almighty with infinant power. If that is so then why shouldn't he be able for him to exist in 3 "persons"?

What is the Trinity?
The Trinity is basically, something like a "book". You can define a book by its height length and width COMBINED. The book's length alone cannot be used to define a book. Those three have to work together to give you the book. The Trinity works in the same way. The Father alone is not God. Nor is The Holy Spirit or The Son (Note: The Father and the Holly Spirit can be used as a DESCRIPTION)
These three work together in perfect harmony and give us God.

WARNING: What I'm saying could sound like a loud of crap.