Jesus is God incarnate (God in the flesh); He is fully man, and fully God.

As to His humanity, just as a baby must grow in wisdom and understanding, the same was true of Jesus. He, however, is God incarnate, and as such, is all knowing (omniscient), all present (omnipresent) and all powerful (omnipotent).

When Jesus became a man, He willfully humbled Himself and limited the independent use of His divine attributes. In the incarnation (when He left heaven and became a man), Christ Jesus surrendered no attribute of Deity, but voluntarily restricted their independent use in keeping with His purpose of living among men and their limitations.

He was omniscient (all-knowing), omnipotent (all-powerful) and omnipresent (all-present) as God the Father granted Him the exercise of these attributes. This is involved in His giving up the glory that He had with the Father before the world was (John 17:5) and His taking on the form of a servant (Philippians 2:6).

As to whether, or not, Jesus could have sinned, some believe that He could have sinned while others believe that He could not have sinned. Some believe that if He could not sin, then there was no purpose in His temptation by Satan. Others, however, say that the purpose was to show that He could not sin.

In His totality as God man, Jesus could be tested, however He could not sin, for God cannot be tempted by evil. (James 1:13)