2 Corinthians 3:18 (ESV)
18 And we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another. For this comes from the Lord who is the Spirit.
John 13:34–35 (ESV)
34 A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. 35 By this all people will know that you are my disciples, if you have love for one another.”
Holiness is not an abstract set of behaviors; it is love for God and love for one another. Holiness from the Father, who is the fountain of love:
1 John 3:16 (ESV)
16 By this we know love, that he laid down his life for us, and we ought to lay down our lives for the brothers.
1 John 1:1–4 (ESV)
1 That which was from the beginning, which we have heard, which we have seen with our eyes, which we looked upon and have touched with our hands, concerning the word of life— 2 the life was made manifest, and we have seen it, and testify to it and proclaim to you the eternal life, which was with the Father and was made manifest to us— 3 that which we have seen and heard we proclaim also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ. 4 And we are writing these things so that our joy may be complete.