John 1:13

John 1:12 talks about people receiving the Lord and being reborn with pure hearts and living as angels. This verse shows where such acceptance and life must come from – first by showing where they do not come from.

"Blood" here means a desire to deny and resist what the Lord teaches, in the Bible and in earlier forms of His Word. "The will of the flesh" means a craving for selfishness and evil. "The will of man" means the false reasoning that erupts from selfishness and justifies it. If we allow our eternal selves to be born of those things – denying the Lord’s leadership, serving ourselves and justifying it in our own minds – we will end up in hell. But if our eternal selves are born "of God," under His leadership and serving His will, then we will be the sons of God described in the previous verse, living in peace and joy in heaven.