I think it is the Holy Spirit at work in those who are willing to receive the Holy Spirit's influence.
There is a famous quote from Gandhi, "I like your Christ, I do not like your Christians. Your Christians are so unlike your Christ."
Those familiar with Gandhi will know that of course he was not a perfect person (and there are no perfect people, so hey), but he dedicated much of his life to trying to help others, even at the expense of himself / his safety. He was moved to study the teachings of Jesus and confessed admiration for Jesus in a quote that would wind up being remembered by millions of people to come.
This is in contrast to those who care nothing for the quality of their character/soul, but may pretend to, and arrogantly mock Jesus without ever knowing Him at all. Much in the political sphere these days revolved around that pseudo-righteousness, "Woe to those who call evil good and good evil, who put darkness for light and light for darkness, who put bitter for sweet and sweet for bitter." The people railing for platforms on the basis that they are 'good' and 'wise' while supporting the mutilated death of millions of unborn infants every year, or those who champion their 'Christian values' by promoting hatred, greed and war. They all know who they are, on both sides, and neither side understands or respects Jesus.
And I mean you track Buddhists long enough in their pursuit of "enlightenment" and "Nirvana" and you will see at least some of them get to a point of realizing it so selfish and nihilistic to be focusing only on their own pseudo-wisdom and rejecting their natural responses to the suffering in their communities, nation, the world, and if they have what it takes spiritually, they turn around and end up with a deeper, genuine wisdom that drives them out into the fray of the world, in all of it's messy complexity, to try to be compassionate to others truly, not just in ego-stroking talk, and bam right there they are taking up the second greatest commandment given by Christ, when all the other teachers of ancient times did not compare in such regards.
It is one of the first things I notice about non-Christians when discussing spiritual or moral matters with them, whether they have an arrogant hostility to Jesus and His Father, or if they have understood and respect His teachings (even if they do not believe what I believe about Him). If they acknowledge the wisdom and compassion in His teachings, which none else in those ancient times rivaled, and they demonstrate the same values, then to me the Holy Spirit works in them.
In John 8, Jesus describes a function of the Holy Spirit (the "Comforter"):
"Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you. And when he is come, he will reprove the world of sin, and of righteousness, and of judgment"
The Holy Spirit reprimands us for our sin, makes us feel guilty. The Holy Spirit is the source of our moral conscience/compass. So that is why when I encounter someone who actually, consistently (save the slip ups we all have, of course) demonstrates the values of compassion, humility, love, forgiveness, mercy, integrity, etc taught by Jesus, I'm like yep, they have the Holy Spirit working in them. They might not be born again yet, I would not know, it is between them and God, but if the Holy Spirit works in them, then it is no place of mine to regard them less than the Holy Spirit does, which has deemed them worthy of Its presence and working within them.
