This is a thoughtful and important question, and the Bible doesn’t address “gambling winnings” directly—but it does give clear principles about the source of wealth, the heart behind giving, and what honors God.

1. God Cares About How Wealth Is Gained

Scripture consistently shows that the source of wealth matters to God:

“The sacrifice of the wicked is detestable to the Lord” (Proverbs 15:8)
“Ill-gotten treasures have no lasting value” (Proverbs 10:2)
“Whoever increases wealth by unjust gain gathers it for another” (Proverbs 28:8)

These verses suggest that God is not pleased simply by receiving something—He also looks at how it was obtained.

If gambling is viewed as rooted in greed, chance, or lack of trust in God’s provision (Hebrews 13:5), then the concern isn’t just the money—it’s the spiritual posture behind it.

2. Giving Does Not “Cleanse” Questionable Actions

The Bible warns against thinking that giving offerings can justify or cover wrongdoing:

“I hate robbery and wrongdoing” (Isaiah 61:8)
“Shall I acquit someone with dishonest scales?” (Micah 6:11)

This implies that offering money to God does not make an unrighteous act righteous.

So, if the gambling itself is sinful, tithing from it doesn’t automatically make it acceptable before God.

3. God Desires a Pure Heart in Giving

At the same time, Scripture emphasizes the heart of the giver:

“Each of you should give what you have decided in your heart… for God loves a cheerful giver” (2 Corinthians 9:7)
“Man looks at the outward appearance, but the Lord looks at the heart” (1 Samuel 16:7)

If the person is repentant and sincerely turning to God, the situation changes. God values humility and transformation more than the money itself.

4. A Biblical Pattern: Repentance Before Offering

There is a strong biblical pattern that repentance should come before offering:

“First be reconciled… then come and offer your gift” (Matthew 5:23–24)

This suggests:
Deal with the spiritual issue first, then bring an offering that reflects a right relationship with God

5. Should the Church Accept It?
The Bible doesn’t give a direct command to churches about this specific case, but principles apply:
The church should not encourage or appear to endorse sin (1 Thessalonians 5:22)
But it also ministers to imperfect people in process.

Wisdom suggests:
The focus should be on discipleship and repentance, not just receiving money
Accepting such giving without addressing the heart issue could be spiritually harmful.

Balanced Biblical Conclusion
If the money is gained through something sinful or spiritually questionable then tithing it does not make the act right before God as God is more concerned with the source, the heart and true repentance.

The most biblically aligned response would be to:
Examine whether the act (gambling) aligns with God’s will.
Repent if convicted.
Then give in a way that reflects honor, obedience, and a clean heart.

Final Thought
God cannot be “honored” with something that comes from a place of disobedience without repentance. He desires integrity over ritual, and obedience over offering (1 Samuel 15:22).