“And just as it is appointed for people to die once—and after this, judgment— so also the Messiah, having been offered once to bear the sins of many, will appear a second time, not to bear sin, but to bring salvation to those who are waiting for Him.”
(Hebrews 9:27–28 HCSB)

Jesus already died for our sins, this was the purpose of his first coming.  There is no longer a necessity for him to come again and die for sins.  His second coming will be for salvation for those who are eagerly waiting for him.  He promised that he would return.  He will return.  He will bring about full and final salvation at his second coming.