Only God knows Himself perfectly. He has revealed Himself sufficiently in His written word and perfectly in His own Son, also recorded in His word. Further attempts at defining God are insults to Him. Since Christ is God in human flesh, artistic depictions of the Incarnate Christ also share the error of presenting the Divine according to human imagination and therefore violate the second commandment as well.
At the time God gave the commandment to Moses, people worshiped all kinds of statues. Aaron and the people even made a golden calf to worship thinking that a calf was a great representation of God because it was strong. In America today, most people do not have the problem of looking at a picture of Jesus and bowing down to it or praying to it, thinking that it is God and that it can hear our prayers. However, when we draw pictures of Jesus, or try to make statues of him, we show only His human nature (as we imagine it) apart from His divine nature. Yet, these two should never be separated.
We make depictions of Jesus that suit our idea of Him, including changing and adapting ethnicity. It's not true to the real Jesus, but instead becomes a Jesus to our liking. It ultimately gives us an image that we rely on in our worship, thinking of the picture instead, and how it makes us feel.
Trekking Through the Testaments relies on the written word of God, illuminated by the Spirit, to sufficiently detail for us the person and character of the Triune God. We also discourage children from making drawings and acting the role of Jesus in plays. Decorations or wall pictures containing pictures of God or Jesus are also discouraged.