It's more that being in control of the Third Impact (or any proper impact really) makes you God. Seele wanted to be God for power, and Gendo wanted to be God to be reunited with his wife. Shinji got Godhood at his lowest point.
This is because Yukikaze is based on (at the time) two novels that's are collections of short stores. It's compacting 16 short stories into 5 episodes.