Timothy knew the Hebrew Scriptures from infancy. But at some point he was convinced by compelling evidence that Jesus was the Messiah.
وَإِيمَانُهُ هٰذَا دَفَعَهُ أَنْ يَعْتَمِدَ وَيُرَافِقَ بُولُسَ فِي ٱلْعَمَلِ ٱلْإِرْسَالِيِّ .‏