“But a certain man named Ananias, with Sapphira his wife, sold a possession, And kept back part of the price, his wife also being privy to it, and brought a certain part, and laid it at the apostles’ feet.” ((Acts 5:1–2))

Motives: why you do what you do. Even what is done for God. Even what is done in the church. Even what is done as a servant of God. Ananias and his wife gave the church a gift. Nothing wrong with that (the church can always use more funds). They also kept back part of their profits from the sale. Nothing wrong with that. So why did Peter condemn them and God kill them?
The answer is simple: their motive was wrong. They wanted to show how spiritual they were by their sacrificial giving to the church, by implying they gave all when in truth they only gave some.
Notice verse three. “But Peter said, Ananias, why hath Satan filled thine heart to lie to the Holy Ghost, and to keep back part of the price of the land?” ((Acts 5:3)) Did they lie to the believers in the local church? Yes. But Peter says this deception before the church was actually a sin against the Holy Spirit. Also, he said what they did was influenced by the Devil. So they died.
I don’t know the motivation for what people do what they do in the church and in their daily lives (I only know my own motives and sometimes I wonder about that). But God does know. Suppose God started doing to us what happened to Ananias and Sapphira, how many of us would be alive? But God is God of grace and compassion. So if we do what we do from wrong motives, He gives us this challenge and a subsequent promise:
“If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.” ((1 John 5:16)) and “If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.” ((1 John 1:9))