God says in Genesis 3:22, “Behold, the man has become like one of us in knowing good and evil…”  Does this suggest that God is evil?

Not necessarily, because there is a difference between knowing about evil and being evil.  Being omniscient (Ps. 147:5; Heb. 4:13), God certainly would know about evil.  However, that does not inherently make him evil.  It is true that it was only due to sin that resulted in Adam and Eve knowing about evil, in that they disobeyed God by eating of the tree of the knowledge of good and evil and thus came to know about evil.  Yet at the same time, sin – evil – is specifically defined as breaking the laws of God (1 John 3:4).  God is inherently good (Ps. 31:19-20; 34:8; Mk. 10:18), as is his will (Rom. 12:2).  Evil only exists due to breaking God’s laws which are inherently good.