Look, when religious people say "God is love," I think they are expressing, as honestly as they are able, a fundamental aspect of their theological and spiritual beliefs -- without any particular regard for a philosophical argument about the nature of God. The phrase is often rooted in Christian teachings, most especially in the Bible, where it is mentioned in verses such as 1 John 4:8, which states, "Anyone who does not love does not know God, because God is love."
The idea, in my (very un-Christian) view is that love, as understood in a divine and perfect sense, is a fundamental attribute of God's nature. It conveys the concept that God's essence is characterized by boundless, selfless, and unconditional love. This perspective suggests that the nature of God is not only loving but also encompasses compassion, mercy, and benevolence.
But this is sadly refuted, throughout the Bible -- both Old and New Testaments -- when God reacts to various human failings with cruel death. You cannot make a claim for "boundless, selfless, and unconditional love" if it has conditions that narrow its effect for your own (God's own Self) reasons. That is where the notion utterly fails for a person of reason.
Further, it seems very clear, to those with some knowledge of animal and human nature, along with neuroscience, that what "love" actually is is an emotion raised in an organism in order to cause the organism to behave in certain ways. Basically, the idea is that organisms are algorithms, and those algorithms generate, from all the sensory and internal information available to them, outputs to guide next actions. And those outputs are very often emotions and feelings, like love, fear, caring, hunger, thirst. They make you close to people, or run away from people, to tend to people who need it (as they may be expected to tend to you when you need it), to eat and to drink....and on and on and on.
And to reduce God to that -- well, is that really where you want to go?