The natural mind assumes that every professor of religion is a true believer. While men may exercise amiable traits that lend themselves to kindness, sincerity, honesty, and spirituality, there is one mark that is indisputable — love for the brethren.
Men may love others for various reasons, but it takes a new heart to love another believer simply because of the other believer’s love for Christ.
Every false religious reason for loving another will perish in time because its source stems totally out of a carnal heart.
Sinners redeemed by the blood of Christ and regenerated by God’s Spirit see (though through a glass darkly) something of the mercy of God in the person of the Lord Jesus Christ. Yet men boast of their great love for others and give reasons that draw praise only to themselves
“By this shall all men know that ye are my disciples, if ye have love one to another.”
By Marvin Stalnaker