I share your opinion on this.
'Condivido' — con-di-VI-do. Stress on the third syllable. From 'condividere' (to share/co-divide).
Use to express agreement with someone's view — slightly more formal than 'sono d'accordo' and implies you've independently arrived at the same conclusion.
'Condividere' literally means 'to share/divide together'. 'Condivido la tua opinione' suggests you hold the same view — you're sharing it with them. This is more active than 'sono d'accordo' — it suggests intellectual convergence.
La penso come te.
I think the same as you.
'Pensarla come' — extremely common and natural Italian agreement phrase
Siamo sulla stessa lunghezza d'onda.
We're on the same wavelength.
'Sulla stessa lunghezza d'onda' — Italian equivalent of 'on the same wavelength'. Very common.
Sono completamente d'accordo.
I completely agree.
Emphatic version of 'sono d'accordo' — 'completamente' adds full endorsement
'Siamo sulla stessa lunghezza d'onda' is used both in personal and professional contexts. It's borrowed from radio broadcasting — the idea of two parties tuned to the same frequency. It signals deep mutual understanding beyond just surface agreement.