We embody what we believe about God through our works, such as with James 2:18 where he said that he would show his faith through his works, so everyone who is a doer of the same works as James believes in God and Jesus. In other words, the way to believe in God is by embodying His likeness through being a doer of His character traits. For example, by being a doer of good works in obedience to God's law we are embodying God's goodness, which is why our good works bring glory to Him (Matthew 5:16), and by embodying God's goodness we are also expressing the belief that God is good. Likewise, the way to believe that God is a good of justice is by being a doer of justice in obedience to Him, the way to believe that God is holy is by being a doer of His instructions for how to be holy as He is holy, we are to be compassionate because believe that God is compassionate, and so forth. This is exactly the same as the way to believe in the Son, who is the radiance of God's glory and the exact likeness of His character (Hebrews 1:3, which he embodied through his works by setting a sinless example for us to follow of how to walk in obedience to God's law.