To preach the Gospel; to spread Christian teachings or convert someone to Christianity through Gospel messages.
From 'gospel' + the suffix -ize (to make or become, or to engage in a process), creating a verb form meaning to engage in gospel preaching.
Adding -ize to a noun creates a verb showing a process—'gospelize' means to turn something or someone toward the Gospel, and historically it was a key word describing Christian missionary work.
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