“If God should promise salvation simply, it is a great matter. But it is a far greater matter when He promises the same salvation amidst manifold dungeons of death. He says: ‘Even while all things shall be out of order and the fear of destruction shall possess all things, only call upon Me and you shall be saved.’
Therefore, however man be swallowed up in the gulf of miseries, yet there is set before him a way to escape. We must also note this universal word, ‘whosoever.’ For God admits all men to Himself without exception, and by this means does He invite them to salvation, just as Paul gathers in the tenth chapter to the Romans (Romans 10:13), and as the prophet had set it down before, ‘O You who hear prayer, to You shall all flesh come.’ (Psalm 65:2)
Therefore, since no man is excluded from calling upon God, the gate of salvation is set open to all men. Neither is there any other thing which keeps us back from entering in except our own unbelief. I speak of all to whom God makes Himself manifest by the gospel.”
–John Calvin, Commentary on the Acts of the Apostles, trans. Christopher Featherstone (Grand Rapids: Baker, 2005), 1: 91-92. Calvin is commenting on Acts 2:21.