Why do Wahabis always talk about Hell Fire and Punishment? Don't they believe in the Mercy of Allah (SWT)?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

First of all, the methodology of the Quran in calling to Islam, advising people, and clarifying matters, is to use both At-Targheeb [encouraging people to do good by mentioning Allah’s promises and rewards] and At-Tarheeb [warning people from evil by mentioning Allah’s threats and punishments]

Allah Says (what means): {Tell my servants that I am indeed the Oft-Forgiving - Most Merciful and that My Chastisement Will be indeed The most grievous Chastisement.} [Quran 15:49-50]

Allah also Says (what means): {The Forgiver of sin, the Acceptor of repentance, the Severe in punishment.} [Quran 40:3].

Allah further Says (what means): {(Nothing is said to you (O Muhammad) except what was said to the Messengers before you. Verily, your Lord is the Possessor of Forgiveness, and (also) the Possessor of Painful punishment).} [Quran 41:43]

Therefore, a Daai'yah (a caller to Islam) should not be limited in his Da’wah to frightening people of Hell and Allah's punishment just as he should not be restricted to speaking of Allah’s Mercy and Forgiveness.

It is for this reason that the Salaf (righteous predecessors) said: He who worships Allah by hope only, is a “Murji’ ” (from the Murjia group) and he who worships Allah by fear only, is a “Khariji” (from the Khawaarij group) .

The Sunni (who follows the Quran and Sunnah) worships Allah by fear, hope, love, desire and awe.

Allah Says about the Prophet Zakariyah and his family (what means): {They used to call on Us with hope and fear, and used to humble themselves before Us).} [Quran 21:90]

The human being's soul tends to like those who calm it down and assure it. It is even inclined to those who awake desire for enjoyment in it and beautify for it the delaying of repentance. But this is a great mistake. A wise person is not satisfied with that; rather, he lives with both fear and hope and does not opt for one of them only.

Finally, there is no group calling itself by this name (Wahabi) and we do not have any knowledge about a group or organization which limits its activity only to speaking of Allah's Wrath and Punishment.

Allah knows best.