Hi Gerald. I'm not sure about 'very specific' sources.

What I'm saying is the position of most (all?) spiritual traditions: Hinduism, Buddhism, Kabbalism, Sufism, Taoism.

It also seems to be the position of Jesus:

"Be ye therefore perfect, even as your Father which is in heaven is perfect" (Matthew 5.48), i.e. seek to make your consciousness the same as the source.

It may also be what Paul means by 'being in Christ': "the recurrent theme of the believer’s close and indissoluble union with the Lord Jesus Christ" (https://biblicalstudies.org.uk/pdf/vox/vol18/in-christ_parsons.pdf)