God can be known
The God of the Bible is separate from the creation, but he has made mankind in such a way that we can understand him. We are able to know God.
"You worship what you do not know; we worship what we know, for salvation is from the Jews." (John 4:22)
This passage tells us that not only can we know what God is like, but that the Jewish scholars of Jesus’ time had understood who God is. Not only that, but Jesus tells us that knowing God is a vital part of the process of salvation:
"And this is eternal life, that they know you the only true God, and Jesus Christ whom you have sent." (John 17:3)
Here Jesus tells us that not only is it possible to know God, knowing God is part of the process of reaching eternal life.
Some churches promote a picture of a God who is three persons, but who is nevertheless one God. The point about this teaching is that it teaches a God who is incomprehensible - it is not possible to know this God. However, the God of the Bible is quite different. He is one God who can be understood, and it is our task to come to know him.