Mark 16:20 And they went out and preached everywhere, the Lord working with them and confirming the word through the accompanying signs. Amen.
I love the way that the Gospel of Mark is ended with such a matter of fact statement that the Lord was with them after His death.
Christ did promise us that we would never be left alone to fend for ourselves but that He would be there and Mark confirms this here that the Lord was still working.
How do we know? Well, when we stop and look at how things are happening or how they have happened we will see that extraordinary things do happen.
They happen just when God needs them to.