God's law if perfect. It is a spiritual law. Holy, just and good. All His commandments are sure and stand fast forever and ever. Given to protect and guide.
Love is the fulfilling of that law.
It is a common practice to use the verse, believe on the Lord Jesus Christ and thou shalt be saved to mean that the mere belief in the fact of Christ's existence, His sacrifice and His saving works, is enough to gain us salvation. People today want to believe in the messenger without believing the message that He brought. Yet Jesus said, If you will enter into life, keep the commandments. Peter said, Repent and you shall receive the gift of the Holy Spirit. To those who obey Him.