Believers can be certain their relationship with the Lord is ongoing and abiding by taking three tests.
1) Applying: We keep His commandments. Not Old Testament Mosaic Laws, but New Testament instructions, precepts, and directives Christ and the apostles taught that made God's will known. Obey God and your love is perfected. You will experience God's love. This display of love will be seen by others and becomes a witness to them.
2) Abiding: Live as Christ lived. Maintain and ongoing fellowship with God. Love is the key to abiding. Love one another as Christ loves us.
3) Affection: There are three aspects that involve a relationship of love.
A Professing Believer Without Love
Ultimately, a professing Christian who hates their brother is not a true disciple. This can apply to those outside of church and to your enemies as well. There is always room for repentance through Christ.
A Professing Believer Who Expresses Love
Ultimately, a professing Christian who loves their brother is a true disciple.
A Professing Believer Who Expresses Hate
These live in a spiritual state of darkness. They walk in darkness. They have no knowledge of where they are going. They are cut off from the light of God that would bring them to repentance and redemption.