From a Buddhist perspective, belief in God is detrimental so there is a motive for Buddhists as well to refute it.
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Buddha: "Others think that God is free creator of all things; clinging to these foolish notions, there is no awakening." [Lankavatara Sutra]
Buddha: "Let us, then, surrender the heresies of worshiping God and praying to him." [Culla Vagga 6:2]
Buddha: "When one falls back on creation by a Supreme Being as being essential ...one dwells bewildered & unprotected. One cannot righteously refer to oneself as a contemplative." [Tittha Sutta]
Buddha: "In this same class the disciples are the earnest disciples of other faiths, who clinging to the notions of such things as, the soul as an external entity, Supreme Atman, Personal God, seek a [belief] that is in harmony with them. ...But none of these, earnest though they be, have gained an insight into the truth of the twofold egolessness and are, therefore, of limited spiritual insights as regards deliverance and non-deliverance; for them there is no emancipation. They have great self-confidence but they can never gain a true knowledge of Nirvana." [Lankavatara Sutra]