Thematic Bible: Who abides in the light

My dearly loved ones, I am not writing to you about a new commandment, but about an old one. [It is the one] you had learned about from the beginning. [Note: This is the commandment to love one another (3:1: II John 5) which Jesus had taught his disciples during His earthly ministry. See Mark 12:31]. This old commandment is the word [of God] which you heard [previously]. Yet, I am [also] writing to you about a new commandment [Note: This commandment was to love one another as Jesus loved them. See John 13:34]; its truth is [being demonstrated] by Christ [perfectly] and [also] by you people [in a lesser measure], because the darkness [of sin] is passing away, and the real light [of righteousness] is already shining [in people's lives]. The person who claims to be living in [harmony with] the light [i.e., by obeying God's truth], and [yet] hates his brother is still [living] in the darkness [of sin]. read more.
[However], the person who loves his brother continues to live in [harmony with] the light [of God's truth], and such a person is not the cause of others stumbling [over his example].