Tevilas Keilim by Non Observant
I was working together with a Ba’al teshuva, kashering his new apartment etc.
I offered to go with him to toivel his new dishes. Later on he told me that his friend who is not religous yet (on his way really just not fully shomer shabbos) went and toiveled all the keilim already.
Is there any neemanus of one’s friend who wouldn’t lie to him?
If we assume that there’s no neemanus what is my obligation?
How do I tell him without hurting anyone’s feelings?
If he knows his friend well and is certain he is reliable and would not lie to him about such a matter, he can rely on him that he was tovel the keilim. This is especially true in your case were he is already somewhat observant and heading in the right direction.
However, it should be clarified that he knows the proper method for tevilas keilim. That it must be fully immersed without any chatzitza, that it must be released from his grip in the water etc..
Igros Moshe Y:D Vol. 1:54, Vol. 2:43. cf. Shu”t Minchas Asher Vol. 2 49:6 who leans towards limiting believing non observant people to the one who personally knows him.