Many do not perceive the difference between the first and second commandments. The first stresses the uniqueness of the Creator God, who is the Source of truth, right values, and standards that will produce right relationships. It deals with what we worship. An idol is something we make and assign value to here on earth, but God comes into our life from beyond this physical realm.
The second commandment covers a specific area of idolatry, God's spirituality. Jesus says we must worship God in spirit and truth (John 4:24). God wants us to worship, be devoted, and respond to what He is and what He is doing, not what we think He looks like. He wants us to emulate His character and the way He lives. The second commandment deals with the way we worship.
The second commandment's most obvious aspect governs the use of physical "helps" or "aids" in worshipping the invisible, spiritual God. It prohibits the use of anything that represents God or could become an object of veneration. It forbids any kind of likeness of Christ such as crucifixes, pictures, and statues.