Agape is the sacrificial love. But agapao is the most important concept of all of Christianity and the closest thing we have to understanding the love of Love (1 John 4:8). Jesus told us that the first and most important commandment is to agapao God with all our heart, soul, mind and strength and to agapao others as ourselves. In the Greek Lexicon it has four definitions: of persons:
to welcome, to entertain, to be fond of, to love dearly.
I stumbled upon that by myself in my own study at Bible College. No one ever told me one of my highest callings was to entertain God!!!