The phrase "strong affirmation" means expressing strong belief or support for something. It shows a high level of certainty and confidence in a statement or an idea. Full definition
«Coming to Salisbury in present circumstances feels like a very strong affirmation of belief in the Christian story on which this cathedral city was founded nearly 800 years ago. (premierchristianity.com)
What I love the very best of this book though is the author's strong affirmation for both life and death, and the indelible link between the two. (bookbrowse.com)
But the sections on international relations contain also many strong affirmations of the duty and opportunity of the church to serve as a unifying force among the nations and as an advocate of those principles of justice and liberty which, if generally observed, would prevent the clash of arms. (religion-online.org)