It was demanded of Abraham, placed in the decalogue given to Moses, confirmed by Jesus in the Sermon on the Mount. We will not be judged by our profession, but by the standard of Christian living which God has set before us. Be ye Holy, for I am Holy. Initial holiness begins at justification, but we are entirely sanctified by the infilling, the coming in, of the Holy Ghost. The great, lasting, and glorious experience at Pentecost was the fulfillment of the promise, that God would take away the stony heart, and give a heart of flesh.
Sin has no allowance, regardless of who commits it.
It must be confessed and repentance made. We may be born again and cleansed from all unrighteousness. This blessed truth is concurrent with the whole tenor of the scriptures and with true experience, yet in the inner and outer life of the sanctified there is a rest, a depth of holiness, a deepness of humility, a perfection of lawfulness, a perfect submission, an overflowing of rivers, not so generously possessed and evidenced by the justified. Happy, contented and perfect in love is the Christian that has found this second rest. His spirit is so enlarged that the entirety of his being may begin to grow in grace, and the fruit of the spirit will not only abound but ripen and mellow into spiritual maturity.