Mark 12:27

[So], He is not God to those who are dead, but [He is] God to those who are alive. You are seriously mistaken."

Mark 12:24

Jesus said to them, "Is not this the reason that you are [so] mistaken, that you do not know [what] the Scriptures [teach] or [how much] power God has?

Romans 4:17

just as it is written [Gen. 17:5], "I [i.e., God] have made you [i.e., Abraham] forefather of many nations." He received this promise in the presence of God, in whom he believed, and who gives life [back] to dead people and who refers to things [promised] as though they were [already] fulfilled.

Romans 14:9

For this is the reason that Christ died and [now] lives again, so that He could be Lord of both those who have [already] died and those who are [still] alive.

Hebrews 3:10

Therefore, I was angry with that generation of people and said, 'They always go astray in their hearts, and they did not understand my ways.'

Hebrews 11:13-16

These people [all] continued to have faith until they died, [even though] they had not obtained [all] the things God had promised, but had [only] seen them and welcomed them from a distance. And they had confessed to being strangers and aliens on earth.

Treasury of Scripture Knowledge

Summary

He is not the God of the dead, but the God of the living: ye therefore do greatly err.

Bible References

Is not

Romans 4:17
just as it is written [Gen. 17:5], "I [i.e., God] have made you [i.e., Abraham] forefather of many nations." He received this promise in the presence of God, in whom he believed, and who gives life [back] to dead people and who refers to things [promised] as though they were [already] fulfilled.
Romans 14:9
For this is the reason that Christ died and [now] lives again, so that He could be Lord of both those who have [already] died and those who are [still] alive.
Hebrews 11:13
These people [all] continued to have faith until they died, [even though] they had not obtained [all] the things God had promised, but had [only] seen them and welcomed them from a distance. And they had confessed to being strangers and aliens on earth.

Ye

Mark 12:24
Jesus said to them, "Is not this the reason that you are [so] mistaken, that you do not know [what] the Scriptures [teach] or [how much] power God has?
Hebrews 3:10
Therefore, I was angry with that generation of people and said, 'They always go astray in their hearts, and they did not understand my ways.'