The belief in God is “plain as day”: easy to comprehend or understand.
“And when waves come over them like canopies, they supplicate Allah , sincere to Him in religion. But when He delivers them to the land, there are [some] of them who are moderate [in faith]. And none rejects Our signs except everyone treacherous and ungrateful.” (Luqman 31:32)
https://youtu.be/eNWGeUA2LHk