Howard Storm, UC Berkeley graduate and professor of arts at Northern Kentucky University, was a long-time atheist.  That is, until he nearly died and found himself heading for hell

The fog thickened as they went on, and it became gradually darker. Overwhelmed with hopelessness, he told them he would go no farther and that they were liars. He could feel their breath on him as they shouted and snarled insults. Then they began to push and shove him about, and he began to fight back. A wild frenzy of taunting, screaming and hitting ensued. As he swung and kicked at them, they bit him.

Even though he couldn’t see anything in the darkness, he was aware there were dozens or hundreds of them all around and over him and that his attempts to fight back only provoked greater merriment. They began to tear off pieces of his flesh, and he realized that he was being taken apart and eaten alive, methodically, slowly, so that their entertainment would last as long as possible. In that wretched state he lay there in the darkness.

So, what do you do when the afterlife you don’t believe in turns out to be real, and you are headed for eternal suffering?

Suddenly remembering a prayer
from childhood Sunday School class, he said, "Yea though I walk in the
valley of the shadow of death, I will fear no evil, for thou art with
me."

To
his amazement, the cruel merciless beings were incited to rage by his
prayer. They screamed at him, ‘There is no God! Nobody can hear you!"
But at the same time they were backing away. He realized that saying
things about God was actually driving them away, and he became more
forceful. They became more rabid, cursing and screaming against God,
but in time, they retreated back into the distant gloom beyond his
hearing.

Alone, destroyed, and yet painfully alive in this horrible place, he yelled out into the darkness, "Jesus, save me."

Far
off in the darkness, he saw a pinpoint of light like the faintest star
in the sky. The star became brighter and brighter. As it came closer,
he realized that he was right in its path, and he might be consumed by
its brilliance.

This
was a living being approximately 8 feet tall and surrounded by an oval
of radiance. The brilliant intensity of the light penetrated his body.
Ecstasy swept away the agony. Tangible hands and arms gently embraced
him and lifted him up. He slowly rose up into the presence of the
light, and the torn pieces of his body miraculously healed before his
eyes.

Now, not all NDEs are like this, but many are.  Of course, this is not objective evidence of the life to come, it is very subjective.  But it seems that at least this atheist approached death very closely and changed his tune.