Why does Paul speak in the present tense about testing?
1 Thessalonians 2:4 (ESV)
4but just as we have been approved by God to be entrusted with the gospel, so we speak, not to please man, but to please God who tests our hearts.
The present tense indicates that Paul thought in terms of a testing that was not confined to the past (say, to the time of his visit to Thessalonica), but continued in the present as well.
4 but just as we have been approved by God to be entrusted with the gospel, so we speak, not to please man, but to please God who tests our hearts.