No, the divinity of Jesus wasn't a later invention or an idea dreamed up by His followers. Instead, right from the first His followers were convinced that Jesus wasn't just another great man but that He was also God in human form.
Why did they believe this? One reason is because Jesus Himself made that claim. To His disciples He said, "I and the Father are one" (John 10:30). On another occasion, He boldly stated, "Anyone who has seen me has seen the Father" (John 14:9). Even His enemies knew of His claim to be God; on one occasion, they accused Him of blasphemy and tried to stone Him, "because you, a mere man, claim to be God" (John 10:33).
Not only did He claim to be God, but He also claimed to have the power to do things only God can do. For example, He said that He had the authority to forgive sins—something only God can do (see Luke 5:24). In addition, His miracles showed He could reverse the laws of nature—again, something only God could do. The ultimate proof of His divinity, however, was His resurrection from the dead.
Why is this important? The reason is because only a divine Savior could save us from our sins—and that is exactly what Jesus Christ did through His death on the cross for us. Don't doubt God's love for you, but by faith open your heart and life to Jesus Christ today.