"Since there is but one covenant, and the Scriptures speak of it as though it were two, we must consider in what particulars the old and new covenants agree and in what they differ." Dr. Zacharias Ursinus

Fancy that! The Scriptures speak of it as though it were two!!

This quote comes from Dr Ursinus, co-author of the Heidelberg Catechism, written with Casper Olevianus, which is by far my favourite catechism. Interesting to note how he openly admits the clarity with which the Scriptures speak of the old and new covenants as two covenants.  

The obvious problem arising from within this quote is that if the old and new covenants are really “but one covenant” then how can this one covenant differ within itself? Cleary these are two covenants just as he admits Scripture testifies.

“24Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar.” Galatians 3:24

“For if that first covenant had been faultless, there would have been no occasion to look for a second.” Hebrews 8:7

“In speaking of a new covenant, he makes the first one obsolete. And what is becoming obsolete and growing old is ready to vanish away.” Hebrews 8:13.

Your brother in Christ, by the blood of the New Covenant-

Shane Becker.

Reference:
"Commentary on the Heidelberg Catechism" by Dr. Zacharias Ursinus.
Presbyterian and Reformed Publishing Company
Phillipsburg, New Jersey.

Quote from page 99. Chapter title, "The Covenant of God", Section Title, "In what do the Old and the New Covenant agree, and in what do they differ?” Book is a reproduction of the Second American Edition which was printed at Columbus, Ohio in 1852.