Takashi Shirogane wasn't someone who believed in several, perhaps HUNDREDS of gods like his Japanese forefathers. He believed in one lone God, who was made up of three different spirits. The Holy Spirit, the Father, and the Son.
When he was younger, he had believed in the Japanese gods, praying to them and offering sacrifices to them.
When his father left him, all that changed. The abandonment sent his mother into a hysterical state, and often times she would become drunk. When this eventually left her dead, his Grandfather same all the way from the states to care for the little seven-year old boy. He took the young boy into the states, raising him into a bright young man with a knowledge of all religions. He gave Shiro the opportunity to choose any religion he wanted, saying that he wouldn't judge whatever his choice was. So Shiro chose Christianity, the religion of his Grandfather.
Once his Grandfather died, Shiro was left alone once more at age seventeen, but this time he had the Garrison. Shiro still prayed to the Lord often, but was more busy once he became a pilot.
When he was nearly nineteen, God turned his mind towards foster care. God sent an image of a young boy with a coal-black mullet. Shiro recognized him as Keith, the child who had refused to show up at the address assigned him. The Lord then turned his mind toward the Rachel Foster Care Foundation.
That was how he officially met Keith.