The term "Common Grace" is often thrown around in reformed circles. What is this concept? What is the scriptural basis for the belief?
The idea of Common Grace is that the grace of God is accessible and granted to all people (ie "common" to all people). This is different from "special" or "saving" grace in that special grace is extended only to the elect.
More clearly, it's the idea that there is grace available and inside everyone. It can be seen in such verses as:
9 “Which of you, if your son asks for bread, will give him a stone? 10 Or if he asks for a fish, will give him a snake?
This is common grace in that everyone (even pagans, idolaters, and abominations) still love their children and will try to take care of them. These parents extend grace even though they are not Christians.
However, even though this grace comes through these "evil" parents, it actually comes from God:
Every good and perfect gift is from above, coming down from the Father of the heavenly lights, who does not change like shifting shadows.
Because of this, God has given grace (and love and mercy) to all humans regardless of their state of salvation or their obedience to him.
This is just "common" grace.
Wikipedia has a lot more regarding it, but that's a simple definition of it and the biblical basis for it.
The doctrine of common grace pertains to the sovereign grace of God bestowed upon all of mankind regardless of their election. In other words, God has always bestowed His graciousness on all people in all parts of the earth at all time. Here are some Bible verses that establish the concept of “common grace”:
“The Lord is good to all; he has compassion on all he has made” (Psalm 145:9).
God causes “his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous” (Matthew 5:45).
God “is kind to the ungrateful and wicked” (Luke 6:35).
“He has shown kindness by giving you rain from heaven and crops in their seasons; he provides you with plenty of food and fills your hearts with joy” (Acts 14:17).
In addition to His compassion, goodness, and kindness, God also sheds His patience upon both the elect and the non-elect. While God’s patience for His own is undoubtedly different from His patience with those whom He has not chosen, God still exercises “longsuffering” toward those whom He has not chosen (Nahum 1:3). Source: https://www.gotquestions.org/common-grace.html
Although the doctrine of common grace has always been clear in Scripture, in 1924, the Christian Reformed Church (CRC) adopted the doctrine of common grace at the Synod of Kalamazoo (Michigan) and formulated what is known as the “three points of common grace.” More information about this is to be found in the link above.