This conviction goes all the way back to Jesus' first disciples, who believed that He wasn't just another man but He was God in human flesh. Thomas, for example, didn't believe Jesus had come back from the dead, but once he saw the risen Christ, he immediately exclaimed, "My Lord and my God!" (John 20:28)—thus affirming Jesus' divine nature.
Why did they believe Jesus was God and not just a man? One reason is because this is what Jesus repeatedly taught about Himself. On one occasion, He declared, "I and the Father are one" (John 10:30). Another time, He stated, "Anyone who has seen me has seen the Father" (John 14:9). Even some of his enemies understood that this was His claim, since "he was even calling God his own Father, making himself equal with God" (John 5:18).
Those first disciples also believed Jesus was divine because of what He did. They witnessed His miracles, and they saw Him exercise authority over the forces of nature. Most of all, they were witnesses to the greatest miracle: His resurrection from the dead, which confirmed His claims.
Why is this important? For one reason: Only a divine Savior could save us from our sins. We cannot save ourselves, nor can anyone else save us. But Christ can—and He did, through His death on the cross for us. Open your heart to Him today, for He alone is "the way and the truth and the life" (John 14:6).