If we keep His Word, His love is perfected in us  -  1 John 2:5

But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.

The love of God does not refer to our love for God but rather to His love for us. The thought is that God’s love toward us has been brought to its goal when we keep His Word. It accomplishes its aim and reaches its end in producing obedience to Him.