Walking in light (truth) causes one to have fellowship with God and the people of God. We are responsible to know the truth of the Scriptures to walk in the truth of God. If we are not walking in fellowship with the people of God we are not walking in fellowship with God. Therefore, it is equally essential that we know who the people of God are. There are many professors of Christianity, but if they are not walking in the light of God as God is in the light we must withdraw ourselves from them. If you are walking with someone and that person is not blessing you to walk in closer fellowship with God then you need to withdraw yourself from that person.