How do you suggest we test our "sincere love"?
Let love be without dissimulation. Abhor that which is evil; cleave to that which is good. (Romans 12:9)
Paul says we can recognize true love by the way we hate evil and cling to good.
Love requires us to have a deep abiding passion for the truth, knowing it , embracing it, obeying it. Just as God hates evil and loves good so should those who know God will love and hate the same things He does.
So how can we know if we truly love others and God as we should? Believers find themselves loving whatever the scripture says is true and good, while also hating everything that is false and evil.
Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are just , whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report ; if there be any virtue , and there be any praise, think on these things. (Philippians 4:8)
Jesus showed us what love looks like with His own life.
A. Do I sincerely love God with all my heart? Like Jesus, we should hate any false beliefs or desires that compete for first place in our hearts.
B. Do I sincerely love God with all my soul? Christ displayed this deep intense love at the Garden of Gethsemane, when He experienced deep grief at the prospect of taking the world's sins upon Himself. (Luke 22:42-44)
C. Do I sincerely love God with all my mind? What we allow to devour and control our thoughts shows what we truly care about.
D. Do I sincerely love God with all my strength? Is all my energy being utilized to satisfy my own will and desires rather than God's will? (John 18:37)
God tells us in His word how to love Him with all our heart, soul, mind, and strength. Hate what God hates and love what God loves. If we can honestly look at our lives and apply these truths, I believe this would sincerely test our love for God.