To love altruistically means to love others without wanting any returns for it. This is very uncommon in this world where those who love others expect them to love them back, to be grateful to them for their love, and to return their favours appropriately when they need them. Jesus said that even sinners loved those who loved them in return (Mt.5:46)! But God's love is altruistic. He loves the good as well as the wicked people and blesses both groups with rain, sun, etc. (v.45). Certainly, the wicked aren't going to do Him any good but only give trouble! He hopes that His goodness may cause the wicked to repent, but that is for their good and not for any gain for Him!
God is able to love everyone irrespective of their response to Him because His nature is to love (1Jn.4:8). And if we have to become able to love like that, first of all we need to be born again and become children of God, and then we need to grow into this love. Ordinary people cannot love in this way even if they decide to love like this because that is not their nature. When we are born into this world we are born with a sinful nature (Ps.51:5). But when we come to Jesus repenting of our sins, we get born again when His nature is born in our spirit (1Pe.1:23), and this nature begins to grow develop.
The world cannot even believe that any man can love without some secret, selfish agenda behind it, because that is the way they know love. But there are many Christians over the centuries who have given themselves to the others in selfless service even to the extent of losing their lives (1Jn.3:16). They were willing to spend and to be spent if only they could bless the others (2Co.12:15). This is how we follow the ultimate example Jesus left us with when He gave Himself for us even when we were His enemies (Ro.5:8).
But it also a fact that even many who are publicly known as 'servants of God' are secretly seeking for their own gain, usually in terms of money, position or fame. Among all those who worked along with him, Paul could find only one, Timothy, who was genuine in his love; all the others had selfish motives of their own (Php.2:19-21). What a pathetic situation!
What is God telling us, as we read this? Do we want to be men and women after His heart, or do we want to travel with our feet in two boats, 'serving God' in front of the people while our heart seeks after our own gain?
What face will we have when we get to look at the face of our Lord? Will we have to put our head down in shame even if we are given the privilege of being with Him, or will we lose that privilege altogether and be cast off as those He does not know (Mt.7:22,23)? If we really love the Lord will we not offer ourselves up to Him as living sacrifices (without seeking any returns) (Ro.12:1)? If we really believe that He has given us every blessing graciously even though what we deserve is hell, how can we have any other response than a wholehearted and joyful service to Him?