Psalm 18:25-26

With the merciful you show yourself merciful;
with the blameless man you show yourself blameless;
with the purified you show yourself pure;
and with the crooked you make yourself seem tortuous

It's easy to think of God as different when comparing the Old and New Testaments, as though God has changed, but it's not God that is changed, it's the covenant. The New Testament is the fulfillment of the Old Testament. Instead of His people failing to keep all of His laws and commandments, Christ has paid the penalty for our failure. Christ has bestowed mercy on us, making us pure and blameless and only those who fail to see that who will continue to see God as tortuous.