God did not condition this that some of us must believe first. He first allowed his son Jesus to be the payment for our sins.
This then is the love of God, unconditional giving, unconditional sacrifice.
This then is our response, to accept those who God has called without reservation according to the flesh.
Love is the keeping of the scriptures in our lives, obedient to God's revelation, the Scriptures.
Love is our loyalty to God and His son Jesus our Lord.
Love is our loyalty to the Brethren of Christ, who are the members of the Church of his Body.
"Ye shall know them by the love they have, one to another."
"For this is the love of God, that ye keep His commandments."
"Faith, hope, love, these three; but the greatest of these is love."