18 Now the birth of J-sus Chr-st was as follows: when His mother Mary had been betrothed to Joseph, before they came together she was found to be with child by the H-ly Sp-rit. 19 And Joseph her husband, being a righteous man and not wanting to disgrace her, planned to send her away secretly. 20 But when he had considered this, behold, an ang-l of the L-rd appeared to him in a dream, saying, “Joseph, son of David, do not be afraid to take Mary as your wife; for the Child who has been conceived in her is of the H-ly Sp-rit. 21 She will bear a Son; and you shall call His name J-sus, for He will save His people from their s-ns.” 22 Now all this took place to fulfill what was spoken by the L-rd through the pr-phet: 23 “Behold, the virgin shall be with child and shall bear a Son, and they shall call His name Imm-nuel,” which translated means, “G-d with us.” 24 And Joseph awoke from his sleep and did as the angel of the Lord commanded him, and took Mary as his wife, 25 but kept her a virgin until she gave birth to a Son; and he called His name J-sus.
Matthew 1:18 – 25 NASB
Why we do what we do.