A 'miracle' can be either a) an unusual or powerful event that is believed to be caused by the power of God 'a divine miracle'. or b) a very amazing or unusual event, thing or achievement. 'It would take a miracle for this team to win.' A 'wonder' is a) something or someone that is very surprising, beautiful or amazing etc. 'The Grand Canyon is one of the natural wonders of the world.' b) something that is surprising or hard to believe. 'It is a wonder we made it this far' (= it is surprising we made it this far). c) A feeling caused by seeing something that is very surprising, beautiful, amazing etc. 'The child's eyes were filled with wonder as she watched the acrobats at the circus.'