Atheist asked: “How can Christians worship their God, who permits unbearable and endless suffering?”
God allows man’s free will to play-out in Time as He uses our propensity for evil as an example to the faithful angelic creation looking-on that obedience to God’s edicts, His perfect will, is of necessity if life and freedom and peace and communion are to exist with sustainability. Our entire existence in Time, which is temporary-finite, is demonstrative of the plague of evil that was initiated in the Kingdom before the creation of matter and Time and that evil was extricated from the Kingdom mandating the creation of this Earth as a repository as that evil is being dealt with partially constrained by Time and physics.
All that you are witnessing, having manifest for 6020-years thus far, is the resultant of disobedience that was initiated in the Spiritual Realm by the Evil One and is currently being played-out in the Physical Realm of Time as our creation has manifest for cause with rapidity. The horror of pestilence, murder, disease, sin, will ultimately act as a bulwark against another rebellion in the Kingdom, the New Jerusalem, as both the faithful angelic creation and the faithful of mankind in Christ Jesus, both possessing the necessity of free will, will know via experiential relevance that obedience to God’s will is infinitely superior to rebellion via narcissism culminating in unconscionable suffering and the “second death.”